Magnetic-field-induced orientational order in the isotropic phase of hard colloidal platelets
NASA Astrophysics Data System (ADS)
van der Beek, D.; Petukhov, A. V.; Davidson, P.; Ferré, J.; Jamet, J. P.; Wensink, H. H.; Vroege, G. J.; Bras, W.; Lekkerkerker, H. N. W.
2006-04-01
The magnetic-field-induced orientational order in the isotropic phase of colloidal gibbsite [Al(OH)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 ?? . 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 ?? . This accounts for the difference between the ?? values provided by the two experimental techniques (SAXS and magneto-optics). The order of magnitude ??˜10-22J/T2 lies in between that of goethite suspensions and that of suspensions of organic particles.
Magnetic field-induced ordering of a polymer-grafted biomembrane-mimetic hydrogel
Firestone, M.A.; Tiede, D.M.; Seifert, S.
2000-03-23
A biomembrane-mimetic complex fluid that spontaneously orients in the presence of a magnetic field to yield a highly ordered lamellar structure is described. Macroscopically oriented lamellae were produced by exploiting the inverted thermoreversible phase transition of the material, that is, by aligning the sample below the phase transition temperature (<16 C)(i.e., in the fluid, hexagonal micellar phase) and warming to produce the lamellar gel phase in a 7.05 T magnetic field. The in situ field-induced alignment was studied by deuterium NMR. The lamellar domains were found to preferentially orient perpendicular to the applied field (negative order). Characterization of the magnetic field-induced anisotropy by polarized optical microscopy and small-angle X-ray scattering/diffraction (SAXS) indicates that it persists even upon field termination. The directional alignment was flipped by 90{degree}, with the lamellar domains oriented parallel to the field (positive order), simply by modifying the composition through the addition of a lanthanide ion (EU{sup 3+}). The system offers the opportunity to spatially organize both membrane and aqueous soluble proteins in an anisotropic matrix, thereby facilitating structure and dynamic studies using a range of techniques, including magnetic resonance (both NMR as well as EPR), optical spectroscopy, and small-angle neutron and X-ray scattering.
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.
NASA Astrophysics Data System (ADS)
Mark, J. Abraham Hudson; Peter, A. John
2014-04-01
Third order susceptibility of third order harmonic generation is investigated in a Zn0.1Mg0.9Se/Zn0.8Mg0.2Se/Zn0.1Mg0.9Se 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.
Magnetic field induced dynamical chaos
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.
Benzene at 1GHz. Magnetic field-induced fine structure.
Heist, L M; Poon, C-D; Samulski, E T; Photinos, D J; Jokisaari, J; Vaara, J; Emsley, J W; Mamone, S; Lelli, M
2015-09-01
The deuterium NMR spectrum of benzene-d6 in a high field spectrometer (1GHz protons) exhibits a magnetic field-induced deuterium quadrupolar splitting ??. The magnitude of ?? observed for the central resonance is smaller than that observed for the (13)C satellite doublets ??'. This difference, ?(??)=??'-??, is due to unresolved fine structure contributions to the respective resonances. We determine the origins of and simulate this difference, and report pulse sequences that exploit the connectivity of the peaks in the (13)C and (2)H spectra to determine the relative signs of the indirect coupling, JCD, and ??. The positive sign found for ?? is consonant with the magnetic field biasing of an isolated benzene molecule-the magnetic energy of the aromatic ring is lowest for configurations where the C6 axis is normal to the field. In the neat liquid the magnitude of ?? is decreased by the pair correlations in this prototypical molecular liquid. PMID:26160011
Antiferroelectric Lattice Distortion Induced by Ferro-quadrupolar Order in DyVO4
NASA Astrophysics Data System (ADS)
Kishimoto, Kazumasa; Wakabayashi, Yusuke; Kimura, Tsuyoshi
The term “multiferroics” was originally coined for materials in which multiple ferroic orders, such as ferromagnetic, ferroelectric, and ferroelastic orders, coexist simultaneously. In recent years, some classes of multiferroics where magnetic and ferroelectric orders coexist have been attracting much attention from both fundamental and technological points of view because the coupling between these two ferroic orders produces intriguing magnetoelectric and magnetodielectric phenomena. Here, we focus on a rare-earth zircon, DyVO4, which exhibits distinct magnetodielectric phenomena owing to another type of ferroic coupling. This compound combines two ferroic orders: “antiferroelectric order” and “quadrupolar order”. We discuss the effect of quadrupolar order (Jahn-Teller effect) on magnetic and dielectric properties in DyVO4 in which the quadrupolar order of Dy 4f electrons induces the antiferroelectric order related to lattice distortion aroung V sites.
Benjamin Ruette; S. Zvyagin; A. P. Pyatakov; A. Bush; J. F. Li; V. I. Belotelov; A. K. Zvezdin; D. Viehland
2004-01-01
Bismuth ferrite is a magnetoelectric material, which simultaneously has polarization and spin orders. We have used electron spin resonance (ESR) as a local probe of the magnetic order in the magnetic-field range of 0 25 T, in the frequency domain of 115 360 GHz, and at a temperature of 4.2 K. The data reveal significant changes in the ESR spectra
NASA Astrophysics Data System (ADS)
Matsumura, Takeshi; Michimura, Shinji; Inami, Toshiya; Hayashi, Yuya; Fushiya, Kengo; Matsuda, Tatsuma D.; Higashinaka, Ryuji; Aoki, Yuji; Sugawara, Hitoshi
2014-04-01
The antiferromagnetic ordered phase in SmRu4P12 below the metal-insulator transition at TMI=16.5 K with an unresolved transition at T*˜14 K has been studied by resonant and nonresonant x-ray diffraction in magnetic fields. In the intermediate phase, a nonresonant Thomson scattering with q =(1,0,0) is induced by applying a magnetic field, which is presumably caused by atomic displacements reflecting the charge order in the p band, as predicted theoretically [R. Shiina, J. Phys. Soc. Jpn. 82, 083713 (2013), 10.7566/JPSJ.82.083713]. Simultaneously, the antiferromagnetic moment of Sm is enhanced along the field direction, which is considered to reflect the staggered ordering of the ?7-?8 crystal-field states (scalar or hexadecapole order). The present results show that the orbital-dependent p-f hybridization in association with the nesting instability in the p band gives rise to the unconventional charge order similarly with PrRu4P12 and PrFe4P12.
Drastic change in transport of entropy with quadrupolar ordering in.
Pourret, A; Behnia, K; Kikuchi, D; Aoki, Y; Sugawara, H; Sato, H
2006-05-01
The antiferroquadrupolar ordering of is explored by probing thermal and thermoelectric transport. The lattice thermal conductivity drastically increases with the ordering, as a consequence of a large drop in carrier concentration and a strong electron-phonon coupling. The low level of carrier density in the ordered state is confirmed by the anomalously large values of the Seebeck and Nernst coefficients. The results are reminiscent of and suggest that both belong to the same class of partial metal-insulator transitions. The magnitude of the Nernst coefficient, larger than in any other metal, indicates a new route for Ettingshausen cooling at Kelvin temperatures. PMID:16712317
Magnetic field induced transition in vanadium spinels.
Mun, E D; Chern, Gia-Wei; Pardo, V; Rivadulla, F; Sinclair, R; Zhou, H D; Zapf, V S; Batista, C D
2014-01-10
We study vanadium spinels AV2O4 (A = Cd,Mg) in pulsed magnetic fields up to 65 T. A jump in magnetization at ?0H?40??T is observed in the single-crystal MgV2O4, indicating a field induced quantum phase transition between two distinct magnetic orders. In the multiferroic CdV2O4, the field induced transition is accompanied by a suppression of the electric polarization. By modeling the magnetic properties in the presence of strong spin-orbit coupling characteristic of vanadium spinels, we show that both features of the field induced transition can be successfully explained by including the effects of the local trigonal crystal field. PMID:24483929
Giant magnetic-field-induced strains in Heusler alloy NiMnGa with modified composition
Zheng, Yufeng
Giant magnetic-field-induced strains in Heusler alloy NiMnGa with modified composition G. H. Wu September 1999 A giant magnetic-field-induced strain MFIS of 3100 ppm has been obtained in Heusler alloy Ni- fort to find a large magnetic-field-induced strain MFIS for developing new actuator materials, recent
Magnetic-field-induced liquid metal droplet manipulation
NASA Astrophysics Data System (ADS)
Kim, Daeyoung; Lee, Jeong-Bong
2015-01-01
We report magnetic-field-induced liquid metal droplet on-demand manipulation by coating a liquid metal with ferromagnetic materials. The gallium-based liquid metal alloy has a challenging drawback that it is instantly oxidized in ambient air, resulting in surface wetting on most surfaces. When the oxidized surface of the droplet is coated with ferromagnetic materials, it is non-wettable and can be controlled by applying an external magnetic field. We coated the surface of a liquid metal droplet with either an electroplated CoNiMnP layer or an iron (Fe) particle by simply rolling the liquid metal droplet on an Fe particle bed. For a paper towel, the minimum required magnetic flux density to initiate movement of the ~8 ?L Fe-particle-coated liquid metal droplet was 50 gauss. Magnetic-field-induced liquid metal droplet manipulation was investigated under both horizontal and vertical magnetic fields. Compared to the CoNiMnP-electroplated liquid metal droplet, the Fe-particle-coated droplet could be well controlled because Fe particles were uniformly coated on the surface of the droplet. With a maximum applied magnetic flux density of ~1,600 gauss, the CoNiMnP layer on the liquid metal broke down, resulting in fragmentation of three smaller droplets, and the Fe particle was detached from the liquid metal surface and was re-coated after the magnetic field had been removed.
Mössbauer Spectroscopy of the Magnetic-Field-Induced Ferroelectric Phase of CuFeO2
NASA Astrophysics Data System (ADS)
Nakamura, Shin; Kobayashi, Yasuhiro; Kitao, Shinji; Seto, Makoto; Fuwa, Akio; Terada, Noriki
2015-02-01
57Fe Mössbauer spectroscopy in an applied magnetic field has been conducted on single crystals of CuFeO2 and CuFe0.965Ga0.035O2 in order to investigate magnetic-field-induced ferroelectric states. The Mössbauer spectra observed under a magnetic field change significantly, corresponding to magnetic-field-induced phase transitions. In the ferroelectric incommensurate (FEIC) phase (7 < Hex < 13 T), the spectrum can be explained by a model with spins distributed at approximately 20, 95, and 160° from the c-axis in the (110) plane. This spin configuration resembles the "complex noncollinear spin configuration (CNC)" model proposed theoretically. In the FEIC phase, the isomer shift is larger, while the quadrupole splitting and average hyperfine field are smaller than those in the collinear four sublattice (4SL, 0 < Hex < 7 T) and five sublattice (5SL, Hex > 13 T) phases. In addition, a noticeable change in the hyperfine field is observed with varying magnetic field. We consider that these changes indicate the change in the electronic state of the Fe3+ ion, possibly modified by a spin-orbit interaction.
A microscopic approach to the magnetic-field-induced deformation of martensite (magnetoplasticity)
NASA Astrophysics Data System (ADS)
Müllner, P.; Chernenko, V. A.; Kostorz, G.
2003-12-01
Deformation experiments were performed in uniaxial compression with a Ni-Mn-Ga single crystal subjected to a magnetic field perpendicular to the stress axis. Depending on the field strength, different stress-strain curves for loading and unloading were obtained. The magnetic-field-induced stress (magneto-stress) and the work done by the corresponding magnetic force were evaluated. In order to understand the relationship between the magneto-mechanical properties and the microstructure, the microscopic processes occurring during magnetic-field-induced deformation are discussed in detail. It turns out that the magnetic work per unit volume and, to some extent, the macroscopic magneto-stress depend on the microstructure, i.e. the spatial distribution of martensite domains. The magnetic threshold field required for triggering magnetoplasticity depends on the twin thickness and is controlled by the mutual interaction of twinning dislocations and their interaction with interfaces. The threshold field can be entirely described within this microscopic approach, taking into account the elementary carrier of magnetoplasticity, which is the twinning dislocation.
Auzinsh, Marcis
Magnetic field induced alignmentorientation conversion: Nonlinear energy shift and predissociation analyzes magnetic field induced alignmentorientation conversion AOC phenomenon caused by simultaneous effect of quadratic terms in Zeeman energy shift and magnetic predissociation PD , producing asymmetry
Field, Timothy R; Bain, Alex D
2014-01-01
Even for large quadrupolar interactions, the powder spectrum of the central transition for a half-integral spin is relatively narrow, because it is unperturbed to first order. However, the second-order perturbation is still orientation dependent, so it generates a characteristic lineshape. This lineshape has both finite step discontinuities and singularities where the spectrum is infinite, in theory. The relative positions of these features are well-known and they play an important role in fitting experimental data. However, there has been relatively little discussion of how high the steps are, so we present explicit formulae for these heights. This gives a full characterization of the features in this lineshape which can lead to an analysis of the spectrum without the usual laborious powder average. The transition frequency, as a function of the orientation angles, shows critical points: maxima, minima and saddle points. The maxima and minima correspond to the step discontinuities and the saddle points generate the singularities. Near a maximum, the contours are ellipses, whose dimensions are determined by the second derivatives of the frequency with respect to the polar and azimuthal angles. The density of points is smooth as the contour levels move up and down, but then drops to zero when a maximum is passed, giving a step. The height of the step is determined by the Hessian matrix-the matrix of all partial second derivatives. The points near the poles and the saddle points require a more detailed analysis, but this can still be done analytically. The resulting formulae are then compared to numerical simulations of the lineshape. We expand this calculation to include a relatively simple case where there is chemical shielding anisotropy and use this to fit experimental (139)La spectra of La2O3. PMID:24992819
Physica B 403 (2008) 909910 Neutron diffraction study of magnetic field induced behavior
Lawrence, Jon
2008-01-01
Physica B 403 (2008) 909910 Neutron diffraction study of magnetic field induced behavior 2 T. We have performed neutron diffraction measurements in magnetic fields up to 6 T on single: Heavy Fermion; Neutron diffraction Ce3Co4Sn13 is a heavy Fermion system which resides close
Artificial magnetic field induced by an evanescent wave.
Mochol, Ma?gorzata; 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
NASA Astrophysics Data System (ADS)
Ho, P.-C.; Yanagisawa, T.; Yuhasz, W. M.; Dooraghi, A. A.; Robinson, C. C.; Butch, N. P.; Baumbach, R. E.; Maple, M. B.
2011-01-01
Superconductivity, magnetic order, and the high field ordered phase have been investigated in the filled skutterudite system Pr1-xNdxOs4Sb12 as a function of composition x in magnetic fields up to 9 T and at temperatures between 50 mK and 10 K. Electrical resistivity measurements indicate that the high field ordered phase, which has been identified with antiferroquadruoplar order, persists to x ~ 0.5. The superconducting critical temperature Tc of PrOs4Sb12 is depressed linearly with Nd concentration to x ~ 0.55, whereas the Curie temperature TFM of NdOs4Sb12 is depressed linearly with Pr composition to (1-x) ~ 0.45. In the superconducting region, the upper critical field Hc2(x,0) is depressed quadratically with x in the range 0 < x ? 0.3, exhibits a kink at x ? 0.3, and then decreases linearly with x in the range 0.3 ? x ? 0.6. The behavior of Hc2(x,0) appears to be a result of pair breaking caused by the applied magnetic field and the exchange field associated with the polarization of the Nd magnetic moments in the superconducting state. From magnetic susceptibility measurements, the correlations between the Nd moments in the superconducting state appear to change from ferromagnetic in the range 0.3 ? x ? 0.6 to antiferromagnetic in the range 0 < x ? 0.3. Specific-heat measurements on a sample with x = 0.45 indicate that magnetic order may occur in the superconducting state, as is also inferred from the depression of Hc2(x,0) with x.
Loginov, D. K. Chegodaev, A. D.
2011-09-15
The nonparabolicity of exciton dispersion due to the mixing of the ground and excited states of an exciton in an external magnetic field perpendicular to the direction of its motion is considered. A model describing this effect is proposed and the nonparabolicity for an exciton in a CdTe crystal is calculated. The magnetic-field induced exciton nonparabolicity is compared with the effect caused by the nonparabolicity of the electron energy dispersion in the conduction band.
High Magnetic Field-Induced Birefringence in Lyotropic Chromonic Liquid Crystals
T. Ostapenko; Yu. Nastishin; J. T. Gleeson; S. N. Sprunt; O. D. Lavrentovich; P. J. Collings
2009-01-01
We studied the effect of magnetic-field induced birefringence of a 14% solution of disodium cromoglycate (DSCG) in water at temperatures above the nematic-isotropic coexistence region. According to Landau-deGennes mean field theory, we expect to find a linear relationship between the inverse of the induced birefringence, deltan, and the quantity (T-T*), where T* is the stability limit of the isotropic phase.
Douliez, J P; Léonard, A; Dufourc, E J
1995-01-01
An expression for the C-C bond order parameter, SCC, of membrane hydrocarbon chains has been derived from the observed C-D bond order parameters. It allows calculation of the probability of each of the C-C bond rotamers and, consequently, the number of gauche defects per chain as well as their projected average length onto the bilayer normal, thus affording the calculation of accurate hydrophobic bilayer thicknesses. The effect of temperature has been studied on dilauroyl-, dimyristoyl-, and dipalmitoylphosphatidylcholine (DLPC, DMPC, DPPC) membranes, as has the effect of cholesterol on DMPC. The salient results are as follows: 1) an odd-even effect is observed for the SCC versus carbon position, k, whose amplitude increases with temperature; 2) calculation of SCC, from nonequivalent deuterons on the sn-2 chain of lipids, SCC2, leads to negative values, indicating the tendency for the C1-C2 bond to be oriented parallel to the bilayer surface; this bond becomes more parallel to the surface as the temperature increases or when cholesterol is added; 3) calculation on the sn-2 chain length can be performed from C1 to Cn, where n is the number of carbon atoms in the chain, and leads to 10.4, 12.2, and 13.8 A for DLPC, DMPC, and DPPC close to the transition temperature, TC, of each of the systems and to 9.4, 10.9, and 12.6 for T-TC = 30-40 degrees C, respectively; 4) separation of intra- and intermolecular motions allows quantitation of the number of gauche defects per chain, which is equal to 1.9, 2.7, and 3.5 for DLPC, DMPC, and DPPC near TC and to 2.7, 3.5, and 4.4 at T-TC = 30-40 degrees C, respectively. Finally, the validity of our model is discussed and compared with previously published models. PMID:7612816
Magnetic-field-induced microwave losses in epitaxial Bi-Sr-Ca-Cu-O films
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.
NASA Astrophysics Data System (ADS)
Karaca, Haluk Ersin
The purpose of this work is to reveal the governing mechanisms responsible for the magnetic field-induced (i) martensite reorientation in Ni 2MnGa single crystals, (ii) stress-assisted phase transformation in Ni2MnGa single crystals and (iii) phase transformation in NiMnCoIn alloys. The ultimate goal of utilizing these mechanisms is to increase the actuation stress levels in magnetic shape memory alloys (MSMAs). Extensive experimental work on magneto-thermo-mechanical (MTM) characterization of these materials enabled us to (i) better understand the ways to increase the actuation stress and strain and decrease the required magnetic field for actuation in MSMAs, (ii) determine the effects of main MTM parameters on reversible magnetic field induced phase transformation, such as magnetocrystalline anisotropy energy (MAE), Zeeman energy (ZE), stress hysteresis, thermal hysteresis, critical stress for the stress induced phase transformation and crystal orientation, (iii) find out the feasibility of employing polycrystal MSMAs, and (iv) formulate a thermodynamical framework to capture the energetics of magnetic field-induced phase transformations in MSMAs. Magnetic shape memory properties of Ni2MnGa single crystals were characterized by monitoring magnetic field-induced strain (MFIS) as a function of compressive stress and stress-induced strain as a function of magnetic field. It is revealed that the selection of the operating temperature with respect to martensite start and Curie temperatures is critical in optimizing actuator performance. The actuation stress of 5 MPa and work output of 157 kJm-3 are obtained by the field-induced variant reorientation in NiMnGa alloys. Reversible and one-way stress-assisted field-induced phase transformations are observed in Ni2MnGa single crystals under low field magnitudes (<0.7T) and resulted in at least an order of magnitude higher actuation stress levels. It is very promising to provide higher work output levels and operating temperatures than variant reorientation mechanisms in NiMnGa alloys. Reversible field-induced phase transformation and shape memory characteristics of NiMnCoIn single crystals are also studied. Reversible field-induced phase transformation is observed only under high magnetic fields (>4T). Necessary magnetic and mechanical conditions, and materials design and selection guidelines are proposed to search for field-induced phase transformation in other ferromagnetic materials that undergo thermoelastic martensitic phase transformation.
Magnetic field-induced transitions in geometrically frustrated Co3V2O8 single crystal
NASA Astrophysics Data System (ADS)
Szymczak, R.; Baran, M.; Diduszko, R.; Fink-Finowicki, J.; Gutowska, M.; Szewczyk, A.; Szymczak, H.
2006-03-01
Magnetization and specific heat of the S=3/2 antiferromagnet on a kagome staircase, Co3V2O8 , were investigated as a function of temperature and magnetic field. The low temperature magnetization data revealed unusual features related to the strongly frustrated spin lattice. Of particular interest were magnetic field induced phase transitions observed for various orientations of the magnetic field. Abrupt macroscopic magnetization jumps induced by a magnetic field directed along the c -axis have been observed below 6K . This effect was also observed for a high enough magnetic field applied in the a-c plane. It is suggested that the jump, observed for H?c is due to a spin reorientation phase transition. It was shown that Co3V2O8 crystals are characterized by a strong magnetocrystalline anisotropy of an easy-plane type. This anisotropy is due to the presence of Co2+ ions in octahedral positions.
Magnetic-field-induced transformation in FeMnGa alloys
Zhu, W.; Liu, E. K.; Feng, L.; Tang, X. D.; Chen, J. L.; Wu, G. H. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Liu, H. Y.; Meng, F. B.; Luo, H. Z. [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China)
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.
NASA Astrophysics Data System (ADS)
Haldar, Krishnendu; Lagoudas, Dimitris C.; Karaman, Ibrahim
2014-09-01
In this work, a continuum based model of the magnetic field induced phase transformation (FIPT) for magnetic shape memory alloys (MSMA) is developed. Hysteretic material behaviors are considered through the introduction of internal state variables. A Gibbs free energy is proposed using group invariant theory and the coupled constitutive equations are derived in a thermodynamically consistent way. An experimental procedure of FIPT in NiMnCoIn MSMA single crystals, which can operate under high blocking stress, is described. The model is then reduced to a 1-D form and the material parameter identification from the experimental results is discussed. Model predictions of magneto-thermo-mechanical loading conditions are presented and compared to experiments.
Magnetic-field-induced rotation of light with orbital angular momentum
NASA Astrophysics Data System (ADS)
Shi, Shuai; Ding, Dong-Sheng; Zhou, Zhi-Yuan; Li, Yan; Zhang, Wei; Shi, Bao-Sen
2015-06-01
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 87Rb 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.
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.
Hattori, Koichi
2015-01-01
We discuss properties of photons in extremely strong magnetic fields induced by the relativistic heavy-ion collisions. We investigate the vacuum birefringence, the real-photon decay, and the photon splitting which are all forbidden in the ordinary vacuum, but become possible in strong magnetic fields. These effects potentially give rise to anisotropies in photon and dilepton spectra.
A dislocation model for the magnetic field induced shape memory effect in Ni2MnGa
Ferreira, Paulo J.
, such as Nitinol. In addition, MSM alloys can easily respond at over 50 times greater fre- quencies (250 Hz) than energy density, which consists of the Zeeman energy density difference, DMB, and the magnetic anisotropy energy density difference, across the twin boundaries. As a result, an applied magnetic field induces
Vakni, David
Magnetic-field-induced orientation of superconducting MgB2 crystallites determined by x; published 4 August 2006 X-ray diffraction studies of fine polycrystalline samples of MgB2 of the applied magnetic field. The MgB2 samples were thoroughly ground to obtain average grain size 510 m
High Magnetic Field-Induced Birefringence in Lyotropic Chromonic Liquid Crystals
NASA Astrophysics Data System (ADS)
Ostapenko, T.; Nastishin, Yu.; Gleeson, J. T.; Sprunt, S. N.; Lavrentovich, O. D.; Collings, P. J.
2009-03-01
We studied the effect of magnetic-field induced birefringence of a 14% solution of disodium cromoglycate (DSCG) in water at temperatures above the nematic-isotropic coexistence region. According to Landau-deGennes mean field theory, we expect to find a linear relationship between the inverse of the induced birefringence, ?n, and the quantity (T-T*), where T* is the stability limit of the isotropic phase. Using the 31 T resistive magnet at the National High Magnetic Field Laboratory, we observed that, as we increase the temperature above the coexistence region, we deviate from this linear dependence. Our data shows that ?n goes to zero, whereas Landau-deGennes predicts that ?n should decrease asymptotically. This may be due to the lack of isodesmic aggregate formation at a finite temperature above the coexistence region.Supported by NSF (DMR-0710544 and DMR-0606160). Work performed at NHMFL, supported by NSF cooperative agreements DMR-0084173, the State of Florida and the DOE.
Magnetic-field-induced DNA strand breaks in brain cells of the rat.
Lai, Henry; Singh, Narendra P
2004-01-01
In previous research, we found that rats acutely (2 hr) exposed to a 60-Hz sinusoidal magnetic field at intensities of 0.1-0.5 millitesla (mT) showed increases in DNA single- and double-strand breaks in their brain cells. Further research showed that these effects could be blocked by pretreating the rats with the free radical scavengers melatonin and N-tert-butyl-alpha-phenylnitrone, suggesting the involvement of free radicals. In the present study, effects of magnetic field exposure on brain cell DNA in the rat were further investigated. Exposure to a 60-Hz magnetic field at 0.01 mT for 24 hr caused a significant increase in DNA single- and double-strand breaks. Prolonging the exposure to 48 hr caused a larger increase. This indicates that the effect is cumulative. In addition, treatment with Trolox (a vitamin E analog) or 7-nitroindazole (a nitric oxide synthase inhibitor) blocked magnetic-field-induced DNA strand breaks. These data further support a role of free radicals on the effects of magnetic fields. Treatment with the iron chelator deferiprone also blocked the effects of magnetic fields on brain cell DNA, suggesting the involvement of iron. Acute magnetic field exposure increased apoptosis and necrosis of brain cells in the rat. We hypothesize that exposure to a 60-Hz magnetic field initiates an iron-mediated process (e.g., the Fenton reaction) that increases free radical formation in brain cells, leading to DNA strand breaks and cell death. This hypothesis could have an important implication for the possible health effects associated with exposure to extremely low-frequency magnetic fields in the public and occupational environments. PMID:15121512
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 (?-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
Karaca, H. E.; Karaman, I.; Basaran, B.; Ren, Y.; Chumlyakov, Y. I.; Maier, H. J.; X-Ray Science Division; Texsas A&M Univ.; Univ. of Kentucky; Siberian Physical-Technical Inst.; Univ. of Paderborn
2009-04-09
Magnetic shape memory alloys (MSMAs) have recently been developed into a new class of functional materials that are capable of magnetic-field-induced actuation, mechanical sensing, magnetic refrigeration, and energy harvesting. In the present work, the magnetic field-induced martensitic phase transformation (FIPT) in Ni{sub 45}Mn{sub 36.5}Co{sub 5}In{sub 13.5} MSMA single crystals is characterized as a new actuation mechanism with potential to result in ultra-high actuation work outputs. The effects of the applied magnetic field on the transformation temperatures, magnetization, and superelastic response are investigated. The magnetic work output of NiMnCoIn alloys is determined to be more than 1 MJ m{sup -3} per Tesla, which is one order of magnitude higher than that of the most well-known MSMAs, i.e., NiMnGa alloys. In addition, the work output of NiMnCoIn alloys is orientation independent, potentially surpassing the need for single crystals, and not limited by a saturation magnetic field, as opposed to NiMnGa MSMAs. Experimental and theoretical transformation strains and magnetostress levels are determined as a function of crystal orientation. It is found that [111]-oriented crystals can demonstrate a magnetostress level of 140 MPa T{sup -1} with 1.2% axial strain under compression. These field-induced stress and strain levels are significantly higher than those from existing piezoelectric and magnetostrictive actuators. A thermodynamical framework is introduced to comprehend the magnetic energy contributions during FIPT. The present work reveals that the magnetic FIPT mechanism is promising for magnetic actuation applications and provides new opportunities for applications requiring high actuation work-outputs with relatively large actuation frequencies. One potential issue is the requirement for relatively high critical magnetic fields and field intervals (1.5-3 T) for the onset of FIPT and for reversible FIPT, respectively.
Karaca, Haluk Ersin
2009-05-15
polycrystal MSMAs, and iv) formulate a thermodynamical framework to capture the energetics of magnetic field-induced phase transformations in MSMAs. Magnetic shape memory properties of Ni2MnGa single crystals were characterized by monitoring magnetic field...
Charles, C.; Boswell, R. W. [Space Plasma, Power and Propulsion Group, Research School of Physical Sciences and Engineering, Australian National University, Australian Capital Territory 0200 (Australia)
2007-11-12
The magnetic-field-induced transition from a simple expansion to a double layer is experimentally investigated in an argon low pressure radio frequency helicon source plasma. When the magnetic field is increased from 30 to 140 G in the plasma source, an abrupt increase in the plasma density and upstream potential is measured at 50 G. In the downstream plasma, the plasma density and potential show a small decrease with increasing magnetic field and no abrupt change. When the upstream jump is measured, simultaneous measurements in the downstream plasma show an ion beam characteristic of a double layer near the source exit.
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
Magnetic-field-induced ferroelectric polarization flop under pressure in TbMnO3
NASA Astrophysics Data System (ADS)
Aoyama, Takuya; Iyama, Ayato; Shimizu, Katsuya; Kimura, Tsuyoshi
2015-03-01
Magnetoelectric properties of multiferroic TbMnO3 with a cycloidal spiral spin order were investigated as functions of applied pressure and magnetic field. We found that a flop of ferroelectric polarization occurs by applying a magnetic field along the a axis under 2-3 GPa below the Néel temperature of Tb moments. A possible origin of the magnetoelectric transition is discussed based on the observed pressure and magnetic-field profiles of the ferroelectric polarization and the dielectric relaxation. This flop would originate from the 90° rotation of the cycloidal spiral plane from the bc plane to the ab plane.
NASA Astrophysics Data System (ADS)
Liu, Dang-Ting; Tian, Ye; Chen, Geng-Hua; Yang, Qian-Sheng
2008-01-01
Based on the results of explicit forms of free energy density for each possible arrangement of magnetization fluxes in large-scale two-dimensional (2D) square ?-loop arrays given by Li et al [2007 Chin. Phys. 16 1450], the field-cooled superconducting phase transition is further investigated by analysing the free energy of the arrays with a simplified symmetrical model. Our analytical result is exactly the same as that obtained in Li's paper by means of numerical calculations. It is shown that the phase transition splits into two branches with either ferromagnetic or anti-ferromagnetic flux ordering, which depends periodically on the strength of external magnetic flux phie through each loop and monotonically on the screen parameter ? of the loops in the arrays. In principle, the diagram of the phase branches is similar to that of its one-dimensional counterpart. The influence of thermal fluctuation on the flux ordering during the transition from normal to superconducting states of the ?-loop arrays is also discussed.
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.
Magnetic-field-induced nematic-nematic phase separation and droplet formation in colloidal goethite
NASA Astrophysics Data System (ADS)
van den Pol, E.; Verhoeff, A. A.; Lupascu, A.; Diaconeasa, M. A.; Davidson, P.; Dozov, I.; Kuipers, B. W. M.; Thies-Weesie, D. M. E.; Vroege, G. J.
2011-05-01
We demonstrate the suitability of polarization microscopy to study the recently discovered (parallel) nematic-(perpendicular) nematic phase separation. This novel type of phase transition is induced by applying an external magnetic field to a nematic liquid crystal of boardlike colloidal goethite and is due to an interplay between the intrinsic magnetic properties of goethite and the collective effect of liquid crystal formation. It is shown that the intense ochre colour of goethite does not preclude the use of polarization microscopy and interference colours, and that dichroism can give valuable qualitative information on the nature of the phases, their anchoring and their sedimentation and order parameter profiles. We also apply these techniques to study 'nematic-nematic tactoids': nematic droplets sedimenting within a nematic medium with mutually perpendicular orientations.
NASA Astrophysics Data System (ADS)
Das, Kalipada; Das, I.
2015-05-01
We report the electronic transport, magneto-transport, and magnetic properties of nanocrystalline Pr0.67Ca0.33MnO3 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 × 107% 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.
NASA Astrophysics Data System (ADS)
Lee, Suyeon; Matsuda, Yasuhiro H.; Naito, Tomoyuki; Nakamura, Daisuke; Takeyama, Shojiro
2015-04-01
The (Pr1?yYy)0.7Ca0.3CoO3 (y ? 0.0625) compounds show a first-order metal-insulator (MI) transition and simultaneous spin-state (SS) transition upon a change in the temperature. We have measured the electrical resistivity of the samples with y = 0.075 (the transition temperature, TMI = 64 K) and 0.10 (TMI = 93 K) in ultrahigh magnetic fields of up to 120 T using a contactless radio-frequency transmission technique. We observed a magnetic-field-induced insulator-metal (IM) transition with large hysteresis below TMI and obtained the temperature-magnetic field phase diagrams. A possible mechanism of the field-induced IM and SS transitions is discussed.
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
Garaj, Slaven
Magnetic-field-induced density of states in MgB2: Spin susceptibility measured by conduction in the superconducting state of high-purity MgB2 fine powders from the intensity of the conduction-electron spin current superconductor models of MgB2. DOI: 10.1103/PhysRevB.72.012511 PACS number s : 74.70.Ad, 74.25.Ha
Morphological model for quadrupolar ? sunspots
NASA Astrophysics Data System (ADS)
Takizawa, K.; Kitai, R.
2014-12-01
Sunspot with umbrae of opposite polarity within a single common penumbra are called ?-spot group (Kunzel, 1960). It has been well known that major flares almost always occur in active region with ?-configuration. Hence, to investigate the formation and evolution of ?-configuration is a key in understanding the major flare activities. However, for the case of ?-spot, emerging flux regions (EFRs) combine intricately to each other. Therefore it is so difficult to decipher the relations between multiple EFRs. To clearly follow the development of the ARs, we should select the ARs which can be observed from the initial emerging stage. Emergence and magnetic evolution of solar active regions (ARs) of ???-type, which are known to be highly flare active (Sammis 2000), were studied with the SOHO/MDI data in the solar cycle 23. 31 ARs, which can be seen from the birth phase, were selected as unbiased samples of our study. From our analysis, we found that successive birth of two emerging flux regions, spatially separated to each other in east-west direction as a series, forming a quadrupolar magnetic configuration, is a typical way of initial development of ??? regions. The ?-configuration was formed by following polarity of western EFR with preceding polarity of eastern EFR. We found 11ARs of quadrupolar type among the sampled 31 ARs. In this work, we propose a plausible model for the quadrupolar type ?-spots as a simple magnetic tube of helical structure, which have downward knot in the mid portion of the flux tube. In nine cases out of 11, the characteristics of the magnetic helicity signs, i.e. the signs of twist and writhe, are consistent with our model.
Field-induced quadrupolar quantum criticality in PrV2Al20
NASA Astrophysics Data System (ADS)
Shimura, Yasuyuki; Tsujimoto, Masaki; Zeng, Bin; Balicas, Luis; Sakai, Akito; Nakatsuji, Satoru
2015-06-01
PrV2Al20 is a heavy-fermion superconductor based on the cubic ?3 doublet that exhibits nonmagnetic quadrupolar ordering below ˜0.6 K. Our magnetotransport study on PrV2Al20 reveals field-induced quadrupolar quantum criticality at ?0Hc˜11 T applied along the [111] direction. Near the critical field ?0Hc required to suppress the quadrupolar state, we find a marked enhancement of the resistivity ? (H ,T ) , a divergent quasiparticle effective mass and concomitant non-Fermi-liquid (NFL) behavior [i.e., ? (T ) ?Tn with n ?0.5 ]. We also observe the Shubnikov-de Haas effect above ?0Hc , indicating effective mass enhancement or m*/m0˜10 . This reveals the competition between the nonmagnetic Kondo effect and the intersite quadrupolar coupling which leads to pronounced NFL behavior in an extensive region of T and ?0H emerging from the quantum-critical point.
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. [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China) and Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996 (United States); X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China); Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States)
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.
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.
NASA Astrophysics Data System (ADS)
Xuan, H. C.; Shen, L. J.; Tang, T.; Cao, Q. Q.; Wang, D. H.; Du, Y. W.
2012-04-01
We have studied the magnetic and magnetoresistance properties in polycrystalline Ni50-xCoxMn32Al18 Heusler alloys. A unique martensitic transformation (MT) from the ferromagnetic austenite to the weak-magnetic martensite phase was obtained and magnetic-field-induced reverse MT was confirmed in these alloys. A magnetic difference up to 45 emu/g was measured across the MT for Ni42Co8Mn32Al18 alloy. In the same quaternary alloy, the large magnetoresistance effect of 67% at 225 K was observed through this field-induced magnetic phase transition.
Magnetic field-induced elastic bending in bilayers of Tb1-xDyxFe2-y and Pb(Zr1-zTiz)O3
NASA Astrophysics Data System (ADS)
Jin, Tao; qichao, Wu; Ning, Zhang
2014-09-01
Magnetic field-induced strain in the magnetoelectric bilayers of Tb1-xDyxFe2-y and Pb(Zr1-zTiz)O3 was studied. A butterfly shaped strain curve was observed on the surface of Pb(Zr1-zTiz)O3. The shape of the strain curve was found to be related to the sample thickness and the volume fraction occupied by the ferroelectrics in the bilayer. Theoretical analysis and experimental results showed that magnetoelastic bending in the bilayer composites was largely responsible for the butterfly strain curve.
NASA Astrophysics Data System (ADS)
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.
2007-03-01
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 (˜50MPa) 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.
Probing Quadrupolar Nuclei by Solid-State NMR Spectroscopy: Recent Advances
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.
Lai, H; Singh, N P
1997-04-01
In previous research, we have found an increase in DNA single- and double-strand breaks in brain cells of rats after acute exposure (two hours) to a sinusoidal 60-Hz magnetic field. The present experiment was carried out to investigate whether treatment with melatonin and the spin-trap compound N-tert-butyl-alpha-phenylnitrone (PBN) could block the effect of magnetic fields on brain cell DNA. Rats were injected with melatonin (1 mg/kg, sc) or PBN (100 mg/kg, ip) immediately before and after two hours of exposure to a 60-Hz magnetic field at an intensity of 0.5 mT. We found that both drug treatments blocked the magnetic field-induced DNA single- and double-strand breaks in brain cells, as assayed by a microgel electrophoresis method. Since melatonin and PBN are efficient free radical scavengers, these data suggest that free radicals may play a role in magnetic field-induced DNA damage. PMID:9213269
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.
Quadrupolar phases of the s=1 bilinear-biquadratic Heisenberg model on the triangular lattice.
Läuchli, Andreas; Mila, Frédéric; Penc, Karlo
2006-08-25
Using mean-field theory, exact diagonalizations, and SU(3) flavor theory, we have precisely mapped out the phase diagram of the S = 1 bilinear-biquadratic Heisenberg model on the triangular lattice in a magnetic field, with emphasis on the quadrupolar phases and their excitations. In particular, we show that ferroquadrupolar order can coexist with short-range helical magnetic order, and that the antiferroquadrupolar phase is characterized by a remarkable 2/3 magnetization plateau, in which one site per triangle retains quadrupolar order while the other two are polarized along the field. Implications for actual S=1 magnets are discussed. PMID:17026330
Magnetic Field-Induced Insulator-Semimetal Transition in a Pyrochlore Nd2Ir2O7
NASA Astrophysics Data System (ADS)
Ueda, K.; Fujioka, J.; Yang, B.-J.; Shiogai, J.; Tsukazaki, A.; Nakamura, S.; Awaji, S.; Nagaosa, N.; Tokura, Y.
2015-07-01
We investigate magnetotransport properties in a single crystal of pyrochore-type Nd2Ir2O7. The metallic conduction is observed on the antiferromagnetic domain walls of the all-in-all-out-type Ir 5 d moment ordered insulating bulk state that can be finely controlled by an external magnetic field along [111]. On the other hand, an applied field along [001] induces the bulk phase transition from insulator to semimetal as a consequence of the field-induced modification of the Nd 4 f and Ir 5 d moment configurations. A theoretical calculation consistently describing the experimentally observed features suggests a variety of exotic topological states as functions of electron correlation and Ir 5 d moment orders, which can be finely tuned by the choice of rare-earth ion and magnetic field, respectively.
Magnetic Field-Induced Insulator-Semimetal Transition in a Pyrochlore Nd_{2}Ir_{2}O_{7}.
Ueda, K; Fujioka, J; Yang, B-J; Shiogai, J; Tsukazaki, A; Nakamura, S; Awaji, S; Nagaosa, N; Tokura, Y
2015-07-31
We investigate magnetotransport properties in a single crystal of pyrochore-type Nd_{2}Ir_{2}O_{7}. The metallic conduction is observed on the antiferromagnetic domain walls of the all-in-all-out-type Ir 5d moment ordered insulating bulk state that can be finely controlled by an external magnetic field along [111]. On the other hand, an applied field along [001] induces the bulk phase transition from insulator to semimetal as a consequence of the field-induced modification of the Nd 4f and Ir 5d moment configurations. A theoretical calculation consistently describing the experimentally observed features suggests a variety of exotic topological states as functions of electron correlation and Ir 5d moment orders, which can be finely tuned by the choice of rare-earth ion and magnetic field, respectively. PMID:26274430
Kiryukhin, V.; Keimer, B. ); Moncton, D.E. )
1995-02-27
Using high resolution x-ray diffraction in magnetic fields up to 12.5 T, we have directly observed a magnetic field driven commensurate-incommensurate transition in a spin-Peierls compound, the organic charge transfer salt tetrathiafulvalene-Cu-[ital bis]-dithiolene (TTF-CuBDT). The field induced transition is weakly first order. The period of the incommensurate lattice modulation in the high field phase is consistent with theoretical predictions.
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.
Magnetic-field-induced shift of the optical band gap in Ni3V2O8
NASA Astrophysics Data System (ADS)
Chen, P.; Holinsworth, B. S.; O'Neal, K. R.; Brinzari, T. V.; Mazumdar, D.; Wang, Y. Q.; McGill, S.; Cava, R. J.; Lorenz, B.; Musfeldt, J. L.
2014-04-01
We employ a magnetic-field driven antiferromagnetic to the fully polarized state transition in Ni3V2O8 to investigate the interaction between spin ordering and driven charge excitations, with special emphasis on the color properties. Our measurements reveal field-induced blue shifts of the band gap that are much larger than that of the Zeeman effect in isolation, anticipating a more greenish appearance in the fully polarized state. This color change is verified with direct photographic images and emanates from charge density differences around the Ni and O centers in high fields.
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.
Neutron diffraction study of the magnetic-field-induced transition in Mn{sub 3}GaC
Çakir, Ö. [Physics Department, Yildiz Technical University, TR-34220 Esenler, Istanbul (Turkey); Physics Engineering Department, Ankara University, TR-06100 Ankara (Turkey); Acet, M.; Farle, M. [Faculty of Physics and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Senyshyn, A. [Forschungsneutronenquelle Heinz Maier-Leibnitz FRM-II, Technische Universität München, D-85747 Garching bei München (Germany)
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.
Magnetic Field-Induced Direct-Indirect Bandgap Crossover in AlxGa1-xAs
NASA Astrophysics Data System (ADS)
Alberi, Kirstin; Mialitsin, Aleksej; Fluegel, Brian; Crooker, Scott; Mascarenhas, Angelo
2015-03-01
Determining the exact alloy composition and energy at which a direct-indirect bandgap crossover occurs in semiconductor alloys is important for engineering optoelectronic materials. However, some amount of error is usually introduced when establishing the crossover from the extrapolation of the direct and indirect bandgap energy trends measured with a discrete set of alloyed samples. We use high magnetic fields up to 58 T to induce the crossover in a single Al0.376Ga0.624As sample, thereby allowing us to precisely identify the crossover energy at low temperature. The onset of the crossover is marked by a reduction in the photoluminescence peak energy and the emergence of an asymmetric peak lineshape resulting from the competition between the radiative lifetime and carrier migration times in the indirect regime. Analysis of the lineshape progression through the crossover confirms that the crossover can be classified as an alloy disorder broadened, first order phase transition. This work was supported by the DOE Office of Science under Contract DE-AC36-08GO28308. The work at LANL was supported by NSF-DMR-1157490 and the State of Florida.
NASA Astrophysics Data System (ADS)
Kiefer, B.; Karaca, H. E.; Lagoudas, D. C.; Karaman, I.
2007-05-01
This paper is concerned with the experimental characterization and the constitutive modeling of magnetic shape memory alloys (MSMA), in terms of their applicability as actuator materials. The key properties that determine the actuation characteristics are the magnetic field-induced strain (MFIS) and the blocking stress. With the goal of increasing the corresponding actuation output, a material selection strategy was followed which was aimed at obtaining a higher magnetocrystalline anisotropy energy, while keeping the detwinning stress low. This was achieved by choosing a composition in which the separation of the Curie temperature and the martensitic transformation temperatures was large, and then selecting an operating temperature just below the phase transformation temperature. In the selected Ni51.1Mn24.0Ga24.9 composition a more than 50% increase of the actuation work output was observed, compared to corresponding data reported in the literature for other off-stoichiometric compositions of the Ni2MnGa intermetallic compound. The second part of the paper describes a phenomenological constitutive model that predicts the MFIS hysteresis curves observed in the first part. The model is concerned with the field-induced reorientation of martensitic variants and changes in the magnetic microstructure. Dissipative effects are captured by introducing internal state variables into the free energy function. In its most general form the contributing energy terms are the elastic strain energy, the Zeeman energy, the magnetocrystalline anisotropy energy and appropriate mixing terms. Typical loading cases are considered and the accuracy of the model predictions is evaluated by comparison with the experimental data presented in the first part of this work.
Basova, Tamara Berezin, Aleksei; Nadolinny, Vladimir; Peisert, Heiko; Chassé, Thomas; Banimuslem, Hikmat; Hassan, Aseel
2013-11-28
The ?-(oxo)bis[tetra-tert-butylphthalocyaninato] aluminum(III) [(tBu){sub 4}PcAl]{sub 2}O films with the crystallites oriented preferably in one direction were obtained via chemical transformation of tetra-tert-butylsubstituted chloroaluminum(III) phthalocyanine (tBu){sub 4}PcAlCl film upon its annealing in magnetic field. A comparative analysis of the influence of post-deposition annealing process without and under applied magnetic field of 1 T, on the orientation and morphology of (tBu){sub 4}PcAlCl and [(tBu){sub 4}PcAl]{sub 2}O films, has been carried out by the methods of UV-vis, Infrared and Raman spectroscopies, XRD as well as atomic force microscopy. The formation of [(tBu){sub 4}PcAl]{sub 2}O films with elongated crystallites having preferential orientation was observed upon heating of the films in magnetic field while annealing without magnetic field under the same conditions does not demonstrate any effect on the structure and morphology of these films. The reasons of the sensitivity of this reaction to the presence of such magnetic field is discussed and studied by electronic paramagnetic resonance spectroscopy.
Level repulsion and the dielectric relaxation in quadrupolar glasses
I. Kanter; H. Sompolinsky
1986-01-01
Dielectric relaxation in quadrupolar glasses is dominated at low temperatures by thermal activation over local anisotropy barriers produced by the quadrupolar freezing. The distribution of barrier heights V vanishes linearly as V-->0 at all temperatures due to the repulsion of levels of the random internal stress tensor. A further shift of V to higher values occurs as T decreases due
Ranabir Das; Anil Kumar
2003-06-14
Physical implementation of Quantum Information Processing (QIP) by liquid-state Nuclear Magnetic Resonance (NMR), 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 have been demonstrated in such systems using transition selective radio-frequency pulses. In this paper we report two novel developments. First, we implement a quantum algorithm which needs coherent superposition of states. Second, we use evolution under quadrupolar coupling to implement multi qubit gates. We implement 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. 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.
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 ?B,1c and ?B,2c between 0 and ? /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 ?B,2c and below ?B,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.
Theoretical studies of the spin dynamics of quadrupolar nuclei at rotational resonance conditions
NASA Astrophysics Data System (ADS)
Walls, Jamie D.; Lim, Kwang Hun; Pines, Alexander
2002-01-01
A theory of the spin dynamics of I=3/2 quadrupolar nuclei in the sudden-passage limit is discussed in relation to the recently observed rotational resonance (RR) effects on the excitation and conversion of triple-quantum coherence in the FASTER multiple-quantum magic-angle spinning (MQMAS) experiments [T. Vosegaard, P. Florian, D. Massiot, and P. J. Grandinetti, J. Chem. Phys. 114, 4618 (2001)]. A novel interaction frame, which combines the quadrupolar interaction with the central transition radio frequency irradiation, is shown to be useful in understanding the complex spin dynamics at and away from RR conditions. Analytical expressions for the Hamiltonian obtained from bimodal Floquet theory are included in order to provide insight into the spin dynamics observed in the FASTER MQMAS experiments. Numerical simulations have been performed and were found to support the theoretical formalism.
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 ?5g(Oyz, Ozx, Oxy) quadrupoles are more induced by the field than the ?3g (O20 and O22) quadrupoles on the ?5u (Tx+y +z?) antiferro-octupole order in phase IV. The problem is that this result is contradictory to a mean-field calculation, which inevitably gives the ?3g quadrupole as the main induced moment. This result indicates that the ?5g quadrupole order is close in energy. We consider that a large fluctuation of the ?5g quadrupole is hidden behind the primary ordering of the ?5u octupole and that the multipolar fluctuation significantly affects the ordering phenomenon.
Kuchel, Philip W; Naumann, Christoph; Puckeridge, Max; Chapman, Bogdan E; Szekely, David
2011-09-01
The NMR z-spectra of 7Li+ and 23Na+ in stretched hydrogels contain five minima, or critical values, with a sharp "dagger" on the central dip. The mathematical representation of such z-spectra from spin-3/2 nuclei contains nine distinct (the total is 15 but there is redundancy of the ±order-numbers) relaxation rate constants that are unique for each of the spin states, up to rank 3, order 3. We present an approach to multiple-parameter-value estimation that exploits the high level of separability of the effects of each of the relaxation rate constants on the features of the z-spectrum. The Markov chain Monte Carlo (MCMC) method is computationally demanding but it yielded statistically robust estimates (low coefficients of variation) of the parameter values. We describe the implementation of the MCMC analysis (in the present context) and posit that it can obviate the need for using multiple-quantum filtered RF-pulse sequences to estimate all relaxation rate constants/times under experimentally favorable, but readily achievable, circumstances. PMID:21742525
NMR-NQR rotation patterns of single crystals with quadrupolar inhomogeneities
NASA Astrophysics Data System (ADS)
Liechti, O.; Kind, R.
The anisotropy of inhomogeneous quadrupolar broadening of NMR-NQR lines can be used to determine distributions of EFG tensors in single crystals. Such distributions are caused by defects, impurities, partial substitutions, and glassy-type ordering. Correlated Gaussian distributions of the EFG tensor elements were found at the N and the Rb sites in the solid solutions [(CH 3) 4N] 2CuBr xCl 4- tx and Rb 1- x(ND 4) xD 2PO 4, respectively. Their temperature dependence in the second system allows for the determination of the glass order parameter of this pseudo-spin glass.
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…
NASA Astrophysics Data System (ADS)
Edén, Mattias; Lo, Andy Y. H.
2009-10-01
Using average Hamiltonian (AH) theory, we analyze recently introduced homonuclear dipolar recoupling pulse sequences for exciting central-transition double-quantum coherences (2QC) between half-integer spin quadrupolar nuclei undergoing magic-angle-spinning. Several previously observed differences among the recoupling schemes concerning their compensation to resonance offsets and radio-frequency (rf) inhomogeneity may qualitatively be rationalized by an AH analysis up to third perturbation order, despite its omission of first-order quadrupolar interactions. General aspects of the engineering of 2Q-recoupling pulse sequences applicable to half-integer spins are discussed, emphasizing the improvements offered from a diversity of supercycles providing enhanced suppression of undesirable AH cross-terms between resonance offsets and rf amplitude errors.
Magnetic order-order phase transitions in itinerant magnets: Fe2-xMnxAs
NASA Astrophysics Data System (ADS)
Valkov, V. I.; Golovchan, A. V.; Dyakonov, V. P.; Szymczak, H.
2011-04-01
Magnetic-field induced magnetic order-order phase transitions in Fe0.69Mn1.31As are studied using first principles calculations of the electronic structure of Fe2-xMnxAs system alloys and a two-band model of itinerant magnets. It is shown that, within this model, the low-temperature ground and magnetic-field induced states can be described in terms of a coexistence of uniform ferromagnetic and periodic antiferromagnetic components of the total magnetic moment of the d-band. The effect of hydrostatic pressure on order-order transitions arises from a structural renormalization of the electron density of states when the material is compressed. The model predicts that collinear ferromagnetism in the Fe2-xMnxAs system is a metastable state, transitions to which can only occur in ultrahigh magnetic fields.
NASA Astrophysics Data System (ADS)
Bini, Donato; Geralico, Andrea
2015-05-01
The influence of an arbitrary spin orientation on the quadrupolar structure of an extended body moving in a Schwarzschild spacetime is investigated. The body dynamics is described by the Mathisson-Papapetrou-Dixon model, without any restriction on the motion or simplifying assumption on the associated spin vector and quadrupole tensor, generalizing previous works. The equations of motion are solved analytically in the limit of small values of the characteristic length scales associated with the spin and quadrupole variables with respect to the characteristic length of the background curvature. The solution provides all corrections to the circular geodesic on the equatorial plane taken as the reference trajectory due to both the dipolar and quadrupolar structures of the body as well as the conditions which the nonvanishing components of the quadrupole tensor must fulfill in order for the problem to be self-consistent.
Donato Bini; Andrea Geralico
2014-12-24
The influence of an arbitrary spin orientation on the quadrupolar structure of an extended body moving in a Schwarzschild spacetime is investigated. The body dynamics is described according to the Mathisson-Papapetrou-Dixon model without any restriction on the motion or simplifying assumption on the associated spin vector and quadrupole tensor, generalizing previous works. The equations of motion are solved analytically in the limit of small values of the characteristic length scales associated with the spin and quadrupole variables with respect to the characteristic length of the background curvature. The solution provides all corrections to the circular geodesic on the equatorial plane taken as the reference trajectory due to both dipolar and quadrupolar structure of the body as well as the conditions which the nonvanishing components of the quadrupole tensor must fulfill in order that the problem be self-consistent.
Donato Bini; Andrea Geralico
2015-09-16
The influence of an arbitrary spin orientation on the quadrupolar structure of an extended body moving in a Schwarzschild spacetime is investigated. The body dynamics is described by the Mathisson-Papapetrou-Dixon model, without any restriction on the motion or simplifying assumption on the associated spin vector and quadrupole tensor, generalizing previous works. The equations of motion are solved analytically in the limit of small values of the characteristic length scales associated with the spin and quadrupole variables with respect to the characteristic length of the background curvature. The solution provides all corrections to the circular geodesic on the equatorial plane taken as the reference trajectory due to both dipolar and quadrupolar structure of the body as well as the conditions which the nonvanishing components of the quadrupole tensor must fulfill in order that the problem be self-consistent.
Ashbrook, Sharon E; Wimperis, Stephen
2005-11-01
The very broad resonances of quadrupolar (spin I > 1/2) nuclei are resolved by magic angle spinning (MAS) into a large number of spinning sidebands, each of which often remains anisotropically broadened. The quadrupolar interaction can be removed to a first-order approximation if the MAS NMR spectrum is acquired in a rotor-synchronized fashion, aliasing the spinning sidebands onto a centreband and thereby increasing the signal-to-noise ratio in the resulting, possibly second-order broadened, spectrum. We discuss the practical aspects of this rotor-synchronization in the direct (t(2)) time domain, demonstrating that the audiofrequency filters in the receiver section of the spectrometer have a significant impact on the precise timings needed in the experiment. We also introduce a novel double-quantum filtered rotor-synchronized experiment for half-integer spin quadrupolar (spin I = 3/2, 5/2, etc.) nuclei that makes use of central-transition-selective inversion pulses to both excite and reconvert double-quantum coherences and yields a simplified spectrum containing only the ST(1) (m(I) = +/-1/2 <--> +/-3/2) satellite-transition lineshapes. For spin I = 5/2 nuclei, such as (17)O and (27)Al, this spectrum may exhibit a significant resolution increase over the conventional central-transition spectrum. PMID:16099187
NASA Astrophysics Data System (ADS)
Machtoub, L. H.; Keimer, B.; Yamada, K.
2005-03-01
We report electronic Raman scattering experiments on a superconducting La1.88Sr0.12CuO4 single crystal in a magnetic field. At low temperatures, the spectral weight of the high-energy two-magnon peak increases linearly with field and is amplified by a factor of more than two at 14 T. The effect disappears at elevated temperatures and is not present in undoped La2CuO4. This observation is discussed in terms of an electronically inhomogeneous state in which the field enhances the volume fraction of a phase with local antiferromagnetic order at the expense of the superconducting phase.
Machtoub, L H; Keimer, B; Yamada, K
2005-03-18
We report electronic Raman scattering experiments on a superconducting La(1.88)Sr(0.12)CuO(4) single crystal in a magnetic field. At low temperatures, the spectral weight of the high-energy two-magnon peak increases linearly with field and is amplified by a factor of more than two at 14 T. The effect disappears at elevated temperatures and is not present in undoped La(2)CuO(4). This observation is discussed in terms of an electronically inhomogeneous state in which the field enhances the volume fraction of a phase with local antiferromagnetic order at the expense of the superconducting phase. PMID:15783513
Dispersive crystal field excitations and quadrupolar interactions in UPd3.
Le, M D; McEwen, K A; Rotter, M; Jensen, J; Bewley, R I; Guidi, T; Fort, D
2012-01-25
We report inelastic neutron scattering measurements and random phase approximation calculations of the dispersive crystal field excitations of UPd(3). The measured spectra at lower energies agree with those calculated using quadrupolar interaction parameters deduced from bulk and x-ray scattering measurements. The more intense excitations arising from the hexagonal sites were used to obtain exchange parameters which proved to be anisotropic. PMID:22156039
Cross polarization for quadrupolar nuclei—Proton to sodium-23
NASA Astrophysics Data System (ADS)
Harris, Robin K.; Nesbitt, Geoffrey J.
The role of cross polarization in magic-angle spinning spectra of quadrupolar nuclei for solids is discussed, using the 1H ? 23Na case as an example. Suitable materials for spectrometer tuning in this mode are proposed and sample spectra presented. Some relaxation experiments on the 23Na signals for borax were carried out, and the selectivity of the cross-polarization experiment is shown for the layer mineral kenyaite.
NASA Astrophysics Data System (ADS)
Bhowmik, R. N.; Vijayasri, G.
2015-06-01
We have studied current-voltage (I-V) characteristics of ?-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 (?VP) 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.
Interaction of Strain and Nuclear Spins in Silicon: Quadrupolar Effects on Ionized Donors
NASA Astrophysics Data System (ADS)
Franke, David P.; Hrubesch, Florian M.; Künzl, Markus; Becker, Hans-Werner; Itoh, Kohei M.; Stutzmann, Martin; Hoehne, Felix; Dreher, Lukas; Brandt, Martin S.
2015-07-01
The nuclear spins of ionized donors in silicon have become an interesting quantum resource due to their very long coherence times. Their perfect isolation, however, comes at a price, since the absence of the donor electron makes the nuclear spin difficult to control. We demonstrate that the quadrupolar interaction allows us to effectively tune the nuclear magnetic resonance of ionized arsenic donors in silicon via strain and determine the two nonzero elements of the S tensor linking strain and electric field gradients in this material to S11=1.5 ×1022 V /m2 and S44=6 ×1022 V /m2 . We find a stronger benefit of dynamical decoupling on the coherence properties of transitions subject to first-order quadrupole shifts than on those subject to only second-order shifts and discuss applications of quadrupole physics including mechanical driving of magnetic resonance, cooling of mechanical resonators, and strain-mediated spin coupling.
Interaction of Strain and Nuclear Spins in Silicon: Quadrupolar Effects on Ionized Donors.
Franke, David P; Hrubesch, Florian M; Künzl, Markus; Becker, Hans-Werner; Itoh, Kohei M; Stutzmann, Martin; Hoehne, Felix; Dreher, Lukas; Brandt, Martin S
2015-07-31
The nuclear spins of ionized donors in silicon have become an interesting quantum resource due to their very long coherence times. Their perfect isolation, however, comes at a price, since the absence of the donor electron makes the nuclear spin difficult to control. We demonstrate that the quadrupolar interaction allows us to effectively tune the nuclear magnetic resonance of ionized arsenic donors in silicon via strain and determine the two nonzero elements of the S tensor linking strain and electric field gradients in this material to S_{11}=1.5×10^{22}??V/m^{2} and S_{44}=6×10^{22}??V/m^{2}. We find a stronger benefit of dynamical decoupling on the coherence properties of transitions subject to first-order quadrupole shifts than on those subject to only second-order shifts and discuss applications of quadrupole physics including mechanical driving of magnetic resonance, cooling of mechanical resonators, and strain-mediated spin coupling. PMID:26274442
NASA Astrophysics Data System (ADS)
Alfred, Roland L.; Londry, Frank A.; March, Raymond E.
1993-06-01
A new theoretical treatment is presented for quadrupolar resonance excitation of ions stored in a quadrupole ion trap. When the ratio of the tickle voltage amplitude to that of the drive potential is small, the equation of ion motion can be expressed in the form of a perturbation series. Exact and approximate solutions to the first-order perturbation eqations are presented. Ion trajectories calculated from these solutions are compared with those calculated by numerical integration. The resonance conditions were found to correspond to a series of angular frequencies given by [omega]u,n = n + [beta]u - [infinity] < n < [infinity]. Some of these, [beta]z[Omega], (1 + [beta]z)[Omega](1 - [beta]z)[Omega] [beta],[Omega], had been observed previously in simulation studies.
Radio-frequency-mediated dipolar recoupling among half-integer quadrupolar spins
Griffin, Robert G.
Radio-frequency-mediated dipolar recoupling among half-integer quadrupolar spins Marc Baldus quadrupolar spins in the presence of an appropriate radio-frequency field. Experimental and theoretical in close spatial proximity. Unfortunately, most spin-1/2 methods involving radio frequency rf irradiation
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.
Spin Squeezing in a Quadrupolar Nuclei NMR System
NASA Astrophysics Data System (ADS)
Auccaise, R.; Araujo-Ferreira, A. G.; Sarthour, R. S.; Oliveira, I. S.; Bonagamba, T. J.; Roditi, I.
2015-01-01
We have produced and characterized spin-squeezed states at a temperature of 26 °C in a nuclear magnetic resonance quadrupolar system. The experiment was carried out on 133Cs nuclei of spin I =7 /2 in a sample of lyotropic liquid crystal. The source of spin squeezing was identified as the interaction between the quadrupole moment of the nuclei and the electric field gradients present within the molecules. We use the spin angular momentum representation to describe formally the nonlinear operators that produce the spin squeezing on a Hilbert space of dimension 2 I +1 =8 . The quantitative and qualitative characterization of this spin-squeezing phenomenon is expressed by a squeezing parameter and squeezing angle developed for the two-mode Bose-Einstein condensate system, as well as by the Wigner quasiprobability distribution function. The generality of the present experimental scheme points to potential applications in solid-state physics.
Quadrupolar relaxation in (KBr)1-x(KCN)x
NASA Astrophysics Data System (ADS)
Hu, Z.; Walton, D.; Vanderwal, J. J.
1988-11-01
Brillouin scattering was used to study the dynamic properties of the mixed crystals (KBr)1-x(KCN)x. By analyzing the frequencies and linewidths of the T2g-symmetry phonon, we were able to determine the cyanide quadrupolar relaxation rate as a function of temperature in the paraelastic regime. We found that this relaxation frequency is proportional to exp(-1/T), rather than proportional to the square root of temperature (?T ), as assumed in Michel's random-field theory. Modifying this theory by incorporating the observed temperature dependence of the relaxation rate improves the agreement with experimental data but is still not adequate. The hierarchically constrained relaxation model of Palmer et al., on the other hand, does provide a phenomenological explanation for our data. In addition, we have determined the value of the random-field strength in these mixed systems.
2H2O quadrupolar splitting used to measure water exchange in erythrocytes.
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 degrees C of 31.5+/-2.2 s(-1) while at 25 degrees C it was approximately 50 s(-1). These values are close to, but less than, those estimated by an NMR relaxation-enhancement method that uses Mn2+ 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. PMID:18291693
Gravitational quadrupolar coupling to equivalence principle test masses: the general case
NASA Astrophysics Data System (ADS)
Lockerbie, N. A.
2002-04-01
This paper discusses the significance of the quadrupolar gravitational force in the context of test masses destined for use in equivalence principle (EP) experiments, such as STEP and MICROSCOPE. The relationship between quadrupolar gravity and rotational inertia for an arbitrary body is analysed, and the special, gravitational, role of a body's principal axes of inertia is revealed. From these considerations the gravitational quadrupolar force acting on a cylindrically symmetrical body, due to a point-like attracting source mass, is derived in terms of the body's mass quadrupole tensor. The result is shown to be in agreement with that obtained from MacCullagh's formula (as the starting point). The theory is then extended to cover the case of a completely arbitrary solid body, and a compact formulation for the quadrupolar force on such a body is derived. A numerical example of a dumb-bell's attraction to a local point-like gravitational source is analysed using this theory. Close agreement is found between the resulting quadrupolar force on the body and the difference between the net and the monopolar forces acting on it, underscoring the utility of the approach. A dynamical technique for experimentally obtaining the mass quadrupole tensors of EP test masses is discussed, and a means of validating the results is noted.
Quantum logical operations for spin 3/2 quadrupolar nuclei monitored by quantum state tomography.
Bonk, F A; deAzevedo, E R; Sarthour, R S; Bulnes, J D; Freitas, J C C; Guimarães, A P; Oliveira, I S; Bonagamba, T J
2005-08-01
This article presents the realization of many self-reversible quantum logic gates using two-qubit quadrupolar spin 3/2 systems. Such operations are theoretically described using propagation matrices for the RF pulses that include the effect of the quadrupolar evolution during the pulses. Experimental demonstrations are performed using a generalized form of the recently developed method for quantum state tomography in spin 3/2 systems. By doing so, the possibility of controlling relative phases of superimposed pseudo-pure states is demonstrated. In addition, many aspects of the effect of the quadrupolar evolution, occurring during the RF pulses, on the quantum operations performance are discussed. Most of the procedures presented can be easily adapted to describe selective pulses of higher spin systems (>3/2) and for spin 1/2 under J couplings. PMID:15921938
NMR quadrupolar system described as Bose-Einstein-condensate-like system
Auccaise, R.; Oliveira, I. S.; Sarthour, R. S. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, Rio de Janeiro 22290-180, Rio de Janeiro (Brazil); Teles, J.; Bonagamba, T. J.; Azevedo, E. R. de [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 369, CEP 13560-970 Sao Carlos, Sao Paulo (Brazil)
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.
PRESTO polarization transfer to quadrupolar nuclei: implications for dynamic nuclear polarization.
Perras, Frédéric A; Kobayashi, Takeshi; Pruski, Marek
2015-09-21
We show both experimentally and numerically on a series of model systems that in experiments involving transfer of magnetization from (1)H to the quadrupolar nuclei under magic-angle-spinning (MAS), the PRESTO technique consistently outperforms traditionally used cross polarization (CP), affording more quantitative intensities, improved lineshapes, better overall sensitivity, and straightforward optimization. This advantage derives from the fact that PRESTO circumvents the convoluted and uncooperative spin dynamics during the CP transfer under MAS, by replacing the spin-locking of quadrupolar nuclei with a single central transition selective 90° pulse and using a symmetry-based recoupling sequence in the (1)H channel. This is of particular importance in the context of dynamic nuclear polarization (DNP) NMR of quadrupolar nuclei, where the efficient transfer of enhanced (1)H polarization is desired to obtain the highest sensitivity. PMID:26266874
PRESTO polarization transfer to quadrupolar nuclei: Implications for dynamic nuclear polarization
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
Dynamic Effects in MAS and MQMAS NMR Spectra of Half-Integer Quadrupolar Nuclei: Calculations and an
Frydman, Lucio
Dynamic Effects in MAS and MQMAS NMR Spectra of Half-Integer Quadrupolar Nuclei: Calculations such as chemical exchange or rotations between inequivalent orientations can affect the magic-angle spinning (MAS) and the multiple-quantum (MQ) MAS NMR spectra of half- integer quadrupolar nuclei. The present paper discusses
NASA Astrophysics Data System (ADS)
Rosenberg, A.; Sandusky, K. W.; Clayman, B. P.; Page, J. B.; Sievers, A. J.
1996-03-01
Far-infrared static electric field measurements have been made for a variety of KI point defects which produce vibrational modes in the pure crystal phonon gap. The extremely small field-induced frequency shifts (<=0.02 cm-1) of the KI gap modes associated with anion impurities were accurately determined with a precision of +/-0.003 cm-1 by using a global analysis method. No frequency shifts were observed for the Rb+ or Cs+ gap modes, up to the maximum applied field of ~100 kV/cm in the [100] direction. Most revealing are the field-induced frequency shifts for the pocket gap modes associated with the Ag+ impurity, which are nearly two orders of magnitude smaller than the field-induced shifts measured for low-frequency Ag+-induced resonant modes. The fact that the pocket-mode displacements are sharply peaked on the (200) family of ions renders them sensitive to the host-lattice anharmonicity near those sites, whereas the resonant modes probe the defect and its nearest neighbors. These E-field measurements and earlier stress-shift measurements are analyzed using a quasiharmonic perturbed shell model. In this approach the effect of either an applied stress or an applied E field is to move the equilibrium positions of the ions, thereby renormalizing the harmonic force constants via the local cubic and quartic anharmonicity. The two types of experiments produce local strains of orthogonal symmetries, and hence provide complementary information. The theoretical analysis of the E field and stress measurements allows us to establish firmly that the Ag+ ion in KI possesses a significant electronic quadrupolar deformability. In turn, this finding strongly supports earlier suggestions that the silver ion quadrupolar deformability is an important feature in the dynamics of other host-silver defect systems and of the silver halides.
New methods and applications in solid-state NMR spectroscopy of quadrupolar nuclei.
Ashbrook, Sharon E; Sneddon, Scott
2014-11-01
Solid-state nuclear magnetic resonance (NMR) spectroscopy has long been established as offering unique atomic-scale and element-specific insight into the structure, disorder, and dynamics of materials. NMR spectra of quadrupolar nuclei (I > (1)/2) are often perceived as being challenging to acquire and to interpret because of the presence of anisotropic broadening arising from the interaction of the electric field gradient and the nuclear electric quadrupole moment, which broadens the spectral lines, often over several megahertz. Despite the vast amount of information contained in the spectral line shapes, the problems with sensitivity and resolution have, until very recently, limited the application of NMR spectroscopy of quadrupolar nuclei in the solid state. In this Perspective, we provide a brief overview of the quadrupolar interaction, describe some of the basic experimental approaches used for acquiring high-resolution NMR spectra, and discuss the information that these spectra can provide. We then describe some interesting recent examples to showcase some of the more exciting and challenging new applications of NMR spectra of quadrupolar nuclei in the fields of energy materials, microporous materials, Earth sciences, and biomaterials. Finally, we consider the possible directions that this highly informative technique may take in the future. PMID:25296129
Quadrupolar nuclear magnetic resonance spectroscopy in solids using frequency-swept echoing pulses
Frydman, Lucio
interactions plays a central role in defining the line shapes observed in both nuclear magnetic resonance NMRQuadrupolar nuclear magnetic resonance spectroscopy in solids using frequency-swept echoing pulses nuclear magnetic resonance NMR . Certain species, particularly quadrupolar spins in sites associated
Quadrupolar traps for charge carriers in the vicinity of lattice vacancies in pentacene crystals
NASA Astrophysics Data System (ADS)
Silinsh, E. A.; Muzikante, I. J.; Rampans, A. J.; Taure, L. F.
1984-04-01
Thermally stimulated current techniques have been used for a selective study of shallow electron and hole traps in pentacene crystals. Asymmetry, observed in electron and hole trapping, is interpreted as evidence for the existence of quadrupolar traps in the vicinity of lattice vacancies, theoretically predicted by Eisenstein and Munn.
Susan M. De Paul; Matthias Ernst; Jay S. Shore; A. Pines; J. F. Stebbins
1997-01-01
The dynamics of cross-polarization from the central transition of a quadrupolar nucleus (Â²â·Al or Â²Â³Na) to a spin-1\\/2 nucleus (Â²â¹Si) during magic-angle spinning and using low-radio-frequency field strengths are analyzed for the mineral low albite. Under these conditions additional complications in the spin-lock behavior of the quadrupolar nucleus and in the cross-polarization process were found experimentally and are examined in
High-Resolution NMR of Quadrupolar Nuclei in the Solid State
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.
Solid Effect Between Quadrupolar Transitions in Dilute Cu-Pd Alloys
NASA Astrophysics Data System (ADS)
Konzelmann, K.; Majer, G.; Seeger, A.
1996-06-01
The paper investigates the Dynamic Solid Effect (DSE) in Nuclear Quadrupole Double Reso-nance (NQDOR) on a system (dilute alloys of CuPd with 8, 42, 210, or 1000 at.ppm Pd) chosen for its simplicity and the possibility to test the theoretical concepts on which the experimental tech-niques (in particular the so-called Berthier-Minier technique for exhibiting the DSE) are based. NQDOR allows to observe the transitions between the Cu nuclear energy levels split by the quadrupolar interaction with the electric field gradients generated by nearby Pd atoms even in dilute alloys, in which the fraction of Cu nuclei experiencing a given field gradient is very small. The DSE permits transitions at frequencies corresponding to the sums or differences of quadrupolar level splittings at neighbouring nuclei and thus gives access to information on the spatial correlation of nuclei accessible to NQDOR studies. The DSE information is shown to be in full accord with the conclusions drawn earlier, on the basis of line-intensity arguments, on the assignment of quadrupo-lar transitions to the first four shells of Cu nuclei surrounding isolated Pd atoms but, in addition, allows to identify the low-frequency NQDOR lines associated with Cu nuclei in the fifth and sixth shells.
Solution deuterium NMR quadrupolar relaxation study of heme mobility in myoglobin
Johnson, R.D.; La Mar, G.N.; Smith, K.M.; Parish, D.W.; Langry, K.C. (Univ. of California, Davis (USA))
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.
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 (?S). 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 ?SDSC 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 ?SDSC = 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 (?SM) induced by magnetic field and calculated using the Maxwell relation yields a ?SM = 46.5J/kg . K, 38% higher than ?SDSC. These entropy results are compared and discussed.
NASA Astrophysics Data System (ADS)
Szmytkowski, Rados?aw; Stefa?ska, Patrycja
2012-04-01
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 perturbing field, the only electric multipole moment induced by the field in the ground state of the atom is the quadrupole one. Using the Sturmian expansion of the generalized Dirac-Coulomb Green function [Szmytkowski, J. Phys. BJPAPEH0953-407510.1088/0953-4075/30/4/007 30, 825 (1997); Szmytkowski, J. Phys. BJPAPEH0953-407510.1088/0953-4075/30/11/023 30, 2747(E) (1997)], we derive a closed-form expression for an induced electric quadrupole moment. The result contains the generalized hypergeometric function 3F2 of the unit argument. Earlier calculations by other authors, based on a nonrelativistic model of the atom, predicted in the low-field region the quadratic dependence of the induced electric quadrupole moment on B.
Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects
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.
Magnetic-field-induced antiferromagnetism in the Kondo lattice
Beach, Kevin S. D. (Kevin Stuart David), 1975-
2004-01-01
The half-filled Kondo lattice model, augmented by a Zeeman term, serves as a useful model of a Kondo insulator in an applied magnetic field. A variational mean field analysis of this system on a square lattice, backed up ...
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.
Magnetic field-induced drug permeability in liposome vesicles.
Liburdy, R P; Tenforde, T S; Magin, R L
1986-10-01
Liposome vesicles maintained in a uniform static magnetic field release a chemotherapeutic drug (ARA-C, MW = 243) at temperatures approaching the phase-transition region where these liposomes are not normally leaky. Drug release is rapid, and a maximum difference between treated and unexposed liposomes of 30% of the total maximal release of ARA-C was observed within 1 min in a magnetic field. Dose-effect studies conducted between 0.01 and 7.5 T (1 T = 10(4) G) reveal that this permeability effect has a sigmoidal dependence on magnetic flux density. The ED50 is 15 mT, with a 95% confidence interval of 6.50-34.9 mT. Magnetic field exposures were conducted using a superconducting magnet with the liposomes maintained at +/- 0.08 degrees C. For comparison, samarium-cobalt permanent magnets induced a comparable drug release at 0.4 T. These results indicate that a static magnetic field of 10 mT or greater can increase passive transport in phospholipid membrane bilayers maintained at or near their membrane phase-transition temperature. Lipid clustering which occurs at prephase-transition temperatures may predispose phospholipid domains to diamagnetic orientation in a magnetic field and thereby facilitate drug release. PMID:3774963
Magnetic-field-induced orientational phase structure transition.
Dou, Yingying; Dong, Shuli; Hao, Jingcheng
2014-02-11
Magnetic field effect on the phase transition at high temperature (from 50 °C) inside the magnetic field has been found in C14G2 (N-tetradecyllactobionamide)/C12EO4 (tetraethylene glycol monododecyl ether)/D2O system. The phase was transited quickly from lamellar phase to isotropic phases [bottom, micellar phase (L1 phase) and top, sponge phase (L3 phase)] induced by a magnetic field, which was demonstrated by (2)H NMR and FF-TEM measurements. The isotropic phases induced by magnetic field were not stable, and the upper L3 phase can recover to lamellar phase after being restored in a 55 °C thermostat outside the magnetic field for about one month. During the mechanism study, the C12EO4 molecule was proved to be the dominant component for the phase transition induced by the magnetic field, while the C14G2 molecule was the auxiliary and just affected the transition speed. The breaking and rebuilding of hydrogen bonds could play an important role in the phase transition and recovering. Moreover, the surfactant concentration had an effect on the speed of phase transiting and phase recovering. These observations could provide an understanding of the phase transition and also the applications for the controlled drug delivery system of bilayer membranes driving, induced by the magnetic field. PMID:24447257
Magnetic field induced spin-wave energy focusing
NASA Astrophysics Data System (ADS)
Perez, Noel; Lopez-Diaz, Luis
2015-07-01
Local temperature variations induced by spin-wave propagation are studied using a model that couples nonuniform magnetization dynamics and heat flow. We show that the remote heating at the sample edge reported recently [T. An et al., Nat. Mater. 12, 549 (2013)], 10.1038/nmat3628 is due to the geometry-induced gradual reduction of the effective field. We demonstrate that the same effect can be achieved by a reduction in the external field instead of a constriction at the edge and, furthermore, that both the location and the amount of energy to be delivered to the lattice can be controlled accurately this way.
Magnetic field induced helical structure in freestanding metal silicate tubes
Yokoi, Hiroyuki; Kuroda, Noritaka; Kakudate, Yozo
2005-05-15
Helical structure on freestanding metal silicate membrane tubes induced by a magnetic field is reported. The phenomenon is observed for iron silicate tubes and cobalt silicate tubes grown under a horizontal field of 2.2 T and a field gradient of 20.5 T/m at the room temperature in contrast to nonregular structure observed at the zero field. Direction control of helicity is achieved by changing the field gradient direction with respect to the field direction. The results are explained in terms of the magnetohydrodynamics effect on the flow of anion discharged from a metal salt solution at the growing end of the silicate tube.
Magnetic-field induced screening effect and collective excitations
Fukushima, Kenji [Department of Physics, Keio University, Kanagawa 223-8522 (Japan)
2011-06-01
We explicitly construct the fermion propagator in a magnetic field background B to take the lowest Landau-level approximation. We analyze the energy and momentum dependence in the polarization tensor and discuss the collective excitations. We find there appear two branches of collective modes in one of two transverse gauge particles; one represents a massive and attenuated gauge particle and the other behaves similar to the zero sound at finite density.
Acquisition of ultra-wideline NMR spectra from quadrupolar nuclei by frequency stepped WURST-QCPMG
NASA Astrophysics Data System (ADS)
O'Dell, Luke A.; Rossini, Aaron J.; Schurko, Robert W.
2009-01-01
Ultra-wideline NMR spectra of quadrupolar nuclei have been obtained using a frequency stepped WURST-QCPMG pulse sequence. This method offers a significant advantage over other frequency stepped techniques due to the much wider excitation bandwidth of the WURST pulses. The incorporation of proton decoupling leads to further signal enhancement in certain cases. The experiment is shown to be applicable to central and satellite transitions of half-integer quadrupoles and also to integer spin nuclei. Frequency stepped WURST-QCPMG is the most efficient way of obtaining ultra-wideline NMR spectra yet reported, and increases the opportunity to study nuclei that were previously considered inaccessible.
pKa tuning in quadrupolar-type two-photon ratiometric fluorescent membrane probes.
Daniel, Jonathan; Mastrodonato, Cristiano; Sourdon, Aude; Clermont, Guillaume; Vabre, Jean-Marie; Goudeau, Bertrand; Voldoire, Hannah; Arbault, Stéphane; Mongin, Olivier; Blanchard-Desce, Mireille
2015-10-01
Two bolaamphiphilic quadrupoles built from a fluorene core conjugated with azine endgroups were designed and successfully used to stain GUV membranes. Their quadrupolar character induces both a shift of the pKa values close to the physiological pH and large two-photon absorption responses (i.e. over 1000 GM for acidic forms). As such they hold promise as ratiometric two-photon pH probes for monitoring slight variations of pH near cell membranes using two-photon excitation in the NIR region. PMID:26226500
del Rosal, Iker; Gutmann, Torsten; Maron, Laurent; Jolibois, Franck; Chaudret, Bruno; Walaszek, Bernadeta; Limbach, Hans-Heinrich; Poteau, Romuald; Buntkowsky, Gerd
2009-07-21
Transition metal (TM) hydrides are of great interest in chemistry because of their reactivity and their potential as catalysts for hydrogenation reactions. 2H solid-state NMR can be used in order to get information about the local environment of hydrogen atoms, and more particularly the coordination mode of hydrides in such complexes. In this work we will show that it is possible to establish at the level of density functional theory (DFT) a viable methodological strategy that allows the determination of 2H NMR parameters, namely the quadrupolar coupling constant (C(Q)) respectively the quadrupolar splitting (deltanuQ) and the asymmetry parameter (etaQ). The reliability of the method (B3PW91-DFT) and basis set effects have been first evaluated for simple organic compounds (benzene and fluorene). A good correlation between experimental and theoretical values is systematically obtained if the large basis set cc-pVTZ is used for the computations. 2H NMR properties of five mononuclear ruthenium complexes (namely Cp*RuD3(PPh3), Tp*RuD(THT)2, Tp*RuD(D2)(THT) and Tp*RuD(D2)2 and RuD2(D2)2(PCy3)2) which exhibit different ligands and hydrides involved in different coordination modes (terminal-H or eta2-H2), have been calculated and compared to previous experimental data. The results obtained are in excellent agreement with experiments. Although 2H NMR spectra are not always easy to analyze, assistance by quantum chemistry calculations allows unambiguous assignment of the signals of such spectra. As far as experiments can be achieved at very low temperatures in order to avoid dynamic effects, this hybrid theoretical/experimental tool may give useful insights in the context of the characterization of ruthenium surfaces or nanoparticles with solid-state NMR. PMID:19842483
A NON-RADIAL ERUPTION IN A QUADRUPOLAR MAGNETIC CONFIGURATION WITH A CORONAL NULL
Sun Xudong; Hoeksema, J. Todd; Liu Yang; Hayashi, Keiji [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Chen Qingrong, E-mail: xudong@sun.stanford.edu [Department of Physics, Stanford University, Stanford, CA 94305 (United States)
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.
High-order Ho multipoles in HoB2C2 observed with soft resonant x-ray diffraction.
Princep, A J; Mulders, A M; Schierle, E; Weschke, E; Hester, J; Hutchison, W D; Tanaka, Y; Terada, N; Narumi, Y; Nakamura, T
2012-02-22
Soft resonant x-ray Bragg diffraction (SRXD) at the Ho M4,5 edges has been used to study Ho 4f multipoles in the combined magnetic and orbitally ordered phase of HoB2C2. A full description of the energy dependence for both ? and ? incident x-rays at two different azimuthal angles, as well as the ratio I(?)/I(?) as a function of azimuthal angle for a selection of energies, allows a determination of the higher order multipole moments of rank 1 (dipole) to 6 (hexacontatetrapole). The Ho 4f multipole moments have been estimated, indicating a dominant hexadecapole (rank 4) order with an almost negligible influence from either the dipole or the octupole magnetic terms. The analysis incorporates both the intra-atomic magnetic and quadrupolar interactions between the 3d core and 4f valence shells as well as the interference of contributions to the scattering that behave differently under time reversal. Comparison of SRXD, neutron diffraction and non-resonant x-ray diffraction shows that the magnetic and quadrupolar order parameters are distinct. The (00½) component of the magnetic order exhibits a Brillouin type increase below the orbital ordering temperature T(Q), while the quadrupolar order increases more sharply. We conclude that the quadrupolar interaction is strong, but quadrupolar order only occurs when the magnetic order gives rise to a quasi-doublet ground state, which results in a lock-in of the orbitals at T(Q). PMID:22301486
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
Anisotropy and quadrupolar effects on dephasing in two-electron spin qubits in GaAs
NASA Astrophysics Data System (ADS)
Botzem, Tim; McNeil, Robert; Bluhm, Hendrik
2015-03-01
Understanding the dynamics of nuclear spins causing decoherence of gate-defined two-electron spin qubits in GaAs is a crucial prerequisite for a potential use in quantum computation. We present B-field dependent Hahn echo measurements giving new insight on the mechanism causing dephasing due to the nuclear spin bath of the host material GaAs. By rotating the magnetic field inplane we discover two effects ultimately limiting coherence times. We find that quadrupolar interaction between nuclear spins and electrical fields contributes to broadening of the nuclear Lamor frequencies, which in turn degrades electron coherence. By rotation the magnetic field towards the [100] direction, we can minimize this effect, but an additional envelope modulation that can be attributed to a electron g-factor anisotropy occurs.
Nonlinear Dependence Observed in Quadrupolar Collective Excitation of a Trapped BEC
NASA Astrophysics Data System (ADS)
Fritsch, A. R.; Tavares, P. E. S.; Bahrami, A.; Tonin, Y. R.; Henn, E. A. L.; Bagnato, V. S.; Telles, G. D.
2015-07-01
We report the experimental observation of the collective excitations induced in a magnetically trapped Rb Bose-Einstein condensate. Low-lying mode excitations were studied by tracking the condensate's center-of-mass displacement, and its aspect ratio as a function of the hold time in the trap. We were able to partially control the modes onset by modulating the amplitude of the additional field gradient used to excite the BEC. The measured excitation frequencies were found to be in good agreement with the literature. We have also found that the modulation amplitude was able to change the phase of the center-of-mass oscillation. Finally, an interesting, nonlinear dependence was observed on the condensate aspect ratio as a function of the perturbing amplitude which induces the quadrupolar mode.
Method to determine the optimal layer number for the quadrupolar fiber coil
NASA Astrophysics Data System (ADS)
Gao, Zhongxing; Zhang, Yonggang; Gao, Wei
2014-08-01
For a high precision interferometric fiber optic gyroscope (IFOG) under temperature control, a short start-up time and small temperature drift are important for its applications. The start-up time and the temperature drift of IFOG with the same fiber length but with a different fiber coil layer number are investigated and compared. Simulation by finite difference time domain method is done to illustrate the existence of optimal layer number for the fiber coil wound by the quadrupolar method. Theoretical analysis is then provided and a closed-form formulation is given to calculate the optimal layer number of the fiber coil, which can effectively reduce both the start-up time and temperature drift of IFOG. Our study is meaningful in improving the thermal performance of the fiber coil.
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.
Solid-state STRAFI NMR probe for material imaging of quadrupolar nuclei
NASA Astrophysics Data System (ADS)
Tang, Joel A.; Zhong, Guiming; Dugar, Sneha; Kitchen, Jason A.; Yang, Yong; Fu, Riqiang
2012-12-01
Stray field imaging (STRAFI) has provided an alternative imaging method to study solid materials that are typically difficult to obtain using conventional MRI methods. For small volume samples, image resolution is a challenge since extremely strong gradients are required to examine narrow slices. Here we present a STRAFI probe for imaging materials with quadrupolar nuclei. Experiments were performed on a 19.6 T magnet which has a fringe field gradient strength of 72 T/m, nearly 50 times stronger than commercial microimagers. We demonstrate the ability to acquire 7Li 1D profiles of liquid and solid state lithium phantoms with clearly resolved features in the micrometer scale and as a practical example a Li ion battery electrode material is also examined.
Pulmonary MRI contrast using Surface Quadrupolar Relaxation (SQUARE) of hyperpolarized 83Kr?
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
A study of the relaxation dynamics in a quadrupolar NMR system using Quantum State Tomography
NASA Astrophysics Data System (ADS)
Auccaise, R.; Teles, J.; Sarthour, R. S.; Bonagamba, T. J.; Oliveira, I. S.; deAzevedo, E. R.
2008-05-01
This article reports a relaxation study in an oriented system containing spin 3/2 nuclei using quantum state tomography (QST). The use of QST allowed evaluating the time evolution of all density matrix elements starting from several initial states. Using an appropriated treatment based on the Redfield theory, the relaxation rate of each density matrix element was measured and the reduced spectral densities that describe the system relaxation were determined. All the experimental data could be well described assuming pure quadrupolar relaxation and reduced spectral densities corresponding to a superposition of slow and fast motions. The data were also analyzed in the context of Quantum Information Processing, where the coherence loss of each qubit of the system was determined using the partial trace operation.
Matyushov, Dmitry V
2012-01-01
Quadrupolar polarization of the interfacial water layer, typically found for water at contact with hydrophobic solutes, couples with the uniform external field to produce the force acting on a suspended particle. This force exists even in the absence of a net particle charge and its direction is consistent with an effectively negative surface charge. The surface charge density scales as $R^{-2}$ with the particle radius $R$, and the corresponding contribution to the $\\zeta$-potential scales as $R^{-1}$. The charge density and $\\zeta$-potential are consistent with the values typically reported for oil drops and bubbles in water at $R\\simeq 3-10$ nm, but decay below those values for larger particles. The study indicates that electrophoretic mobility without charge is possible, but is limited to relatively small particles a few nanometers in size.
Quadrupolar effects in PrCu{sub 2}Si{sub 2}
Osborn, R.; Goremychkin, E.A.
1994-05-01
As part of a systematic study of the crystal field (CF) potential in RCu{sub 2}Si{sub 2} compounds (R = Ce, Pr, Nd, Tb, Ho, Er) using inelastic neutron scattering, we have determined the CF level scheme and potential in the antiferromagnet PrCu{sub 2}Si{sub 2} both above and below T{sub N}. There have been recent speculations that the quadrupole moment of PrCu{sub 2}Si{sub 2} has been quenched by the quadrupolar Kondo effect. Using the CF potential derived from our results, we have calculated the quadrupole moment Q{sub 2} of PrCu{sub 2}Si{sub 2} and compared it to the other members of the RCu{sub 2}Si{sub 2} series. The temperature dependence of the quadrupole moment of PrCu{sub 2}Si{sub 2} is significantly weaker-than all the other compounds eg. it is approximately five times smaller than HoCu{sub 2}Si{sub 2}. Therefore, it is the CF potential which is responsible for quenching Q{sub 2} at low temperature rather than a quadrupolar Kondo effect. Furthermore, the CF Schottky contribution to C/T {nu} T{sup 2} is approximately linear above T{sub N} and explains the anomalously high linear term in the specific heat. However, the evolution of the CF potential across the rare earth series provides evidence of an enhanced hybridization contribution to the CF potential of PrCu{sub 2}Si{sub 2}, intermediate between the heavy fermion CeCu{sub 2}Si{sub 2} and the other rare earth compounds.
Tarasek, Matthew R; Kempf, James G
2010-10-01
Radiofrequency electric (E) fields oscillating at twice the usual NMR frequency (2?(0)) can induce double-quantum transitions in quadrupolar nuclei, an NMR Stark effect. Characterization of such is of interest to aid understanding of electrostatic effects in NMR spectra. Calibration of Stark responses to an applied electric field may also be used to assess native fields within molecules and materials. We present high-field (14.1 T), room-temperature NMR experiments to calibrate the 2?(0) Stark response in crystalline GaAs. This system presents an important test of current techniques and conditions, as historical studies at low field (500-900 mT) and low temperature (77 K) provide a basis for comparison. Our measurements of steady state response reveal the quadrupolar Stark tuning rate for (69)Ga in this material. The value, ?(Q) = (11.5 ± 0.1) × 10(12) m(-1), is 3.6 times larger than the most-reliable prior result. In the process, we also uncovered a previously unobserved double-quantum steady state coherence. It appears as a completely separable dispersive signal component in quadrature-detected presaturation spectra versus offset from 2?(0). The new component may eventually afford an independent route to calibrating ?(Q). Finally, we demonstrated exceptional agreement with theory of the orientation-dependent Stark response for rotation of the sample relative to B(0) over a range of 90° and for E-field amplitudes from 30-180 V/cm. PMID:20839890
Frydman, Lucio
Dynamic Effects on the Powder Line Shapes of Half-Integer Quadrupolar Nuclei: A Solid-State NMR influence the NMR powder patterns of half-integer quad- rupolar nuclei. Treatments on the effects of motions
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.
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
NASA Astrophysics Data System (ADS)
Barzoukas, Marguerite; Blanchard-Desce, Mireille H.
2001-12-01
Recent reports of push-pull dipolar and quadrupolar chromophores with enhanced two-photon absorption have generated considerable interest in these two molecular systems. Two photon absorption is related to the imaginary part of the two-photon resonant cubic hyperpolarizability Im[(gamma) ((omega) )]. In this work, we have described both push-pull dipolar and quadrupolar chromophores using multi valence-bond states models based on measurable parameters of the valence-bond forms. We have derived analytical expressions of their non-resonant static cubic hyperpolarizability (gamma) (0) and of Im[(gamma) ((omega) )]. Comparison between the transparency / Im[(gamma) ((omega) )] trade-off and Im[(gamma) ((omega) )] / (gamma) (0) correlation helps understand the advantages and drawbacks of each of these two push-pull systems. Furthermore by understanding how the valence-bond parameters are related to the molecular structure and its environment, it is possible to predict how Im[(gamma) ((omega) )] will be affected by changing either the conjugation size, the donor-acceptor pair or the solvent polarity for both of these push-pull systems. The results of this study suggest common guidelines for the molecular engineering of both the push-pull dipolar and quadrupolar chromophores.
Suter; Mali; Roos; Brinkmann
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 ||Deltam || = 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, 32, 52, 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 (17)O (I = 52) in the high-temperature superconductor YBa(2)Cu(4)O(8): the (17)O spin-lattice relaxation rate consists of magnetic as well as quadrupolar contributions. Copyright 2000 Academic Press. PMID:10729252
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 ??m? = 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.
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.
NSDL National Science Digital Library
This activity helps students develop a sense of the relative size of quantities in time, length and mass. Learners rank their estimates of given measures in order from least to greatest and justify their decisions. The Teachers' Notes page includes suggestions for implementation, discussion questions, ideas for extension and support, printable cards (pdf), and a link to a related problem, "In Order" (cataloged separately). The solutions page shows that students used standard units of measure to make their comparisons.
NASA Astrophysics Data System (ADS)
Chen, Ying; Cao, Duxia; Wang, Shasha; Zhang, Changqiao; Liu, Zhiqiang
2010-04-01
A new acceptor-?-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 ( ? = 1150 GM at 730 nm in hexane), high emission quantum yield ( ? = 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.
Furo, I.; Halle, B.; Quist, P.O.; Wong, Tuck C. (Univ. of Lund (Sweden))
1990-03-22
In the first systematic application of the two-dimensional quadrupolar echo (2DQE) method, we study the {sup 23}Na NMR relaxation behavior of counterions in the reversed hexagonal mesophase of the AOT/D{sub 2}O/isooctane system, consisting of long cylindrical aggregates with the water and ions on the inside. Using a combination of relaxation experiments, performed on magnetically aligned samples, we determine the three spectral densities at two sample orientations. The orientational dependence of the spectra densities allows us to separate contributions from different types of molecular motion.
NASA Astrophysics Data System (ADS)
Tang, Joel A.; O'Dell, Luke A.; Aguiar, Pedro M.; Lucier, Bryan E. G.; Sakellariou, Dimitris; Schurko, Robert W.
2008-12-01
The uses of microcoils and WURST pulses for acquiring ultra-wideline (UW) NMR spectra of half-integer quadrupolar nuclei are explored. Using large rf field strengths or frequency-swept pulses, UW spectra (breadth > 300 kHz) can be acquired without changing the transmitter frequency. The efficiency of UWNMR spectroscopy improves for both microcoil and WURST pulse experiments compared to rectangular-pulse experiments using a 4.0 mm coil. Microcoils are also used to acquire UW spectra of an unreceptive nucleus ( 91Zr) and a spectrum comprised of both central and satellite transitions ( 59Co).
Transmission of order in some unusual dilute systems
NASA Technical Reports Server (NTRS)
Adler, Joan; Palmer, R. G.; Meyer, H.
1987-01-01
As a system is diluted, the critical temperature T may fall to zero at a concentration X sub c greater than the percolation concentration, because mere connectivity does not guarantee the transmission of order even at T = 0. Detailed results, including bounds on X sub c, are presented for the three-state Potts antiferromagnet on a triangular lattice and for quadrupolar models of (o-H2)x(p-H2)1-x mixtures on fcc and triangular lattices.
Edén, Mattias
2010-05-01
Three two-dimensional (2D) NMR homonuclear correlation techniques invoking double-quantum (2Q) filtration of the central transitions of half-integer spins are evaluated numerically and experimentally. They correlate directly detected single-quantum (1Q) coherences in the t(2) domain with either of 1Q, two-spin 2Q or single-spin multiple-quantum coherence-evolutions in the indirect (t(1)) dimension. We employ experimental (23)Na and (27)Al NMR on sodium sulfite and the natural mineral sillimanite (SiAl(2)O(5)), in conjunction with simulated 2D spectra from pairs of dipolar-recoupled spins-3/2 and 5/2 at different external magnetic fields, to compare the correlation strategies from the viewpoints of 2D spectral resolution, signal sensitivity, implementational aspects and their relative merits for establishing internuclear proximities and quadrupolar tensor orientations. PMID:20202872
Li, Zhihong; Meng, Zhuo; Liu, Tiegen; Yao, X Steve
2013-01-28
We introduce a parameter called pointing error thermal sensitivity (PETS) for quantitatively determining the quality of a quadrupolar (QAD) fiber coil under radial temperature variations. We show both analytically and experimentally that the pointing error of a fiber gyro incorporating the fiber coil is linearly proportional to the final radial thermal gradient on the coil, with PETS as the proportional constant. We further show that PETS is linearly proportional to another parameter called effective asymmetric length of the coil. By thermally inducing different radial thermal gradients on the fiber coil and measuring the corresponding pointing errors in a gyroscopic measurement setup, we can confidently determine the PETS of the fiber coil and its associated effective asymmetric length caused by imperfections in coil winding. Consequently, we are able to precisely trim the coil to achieve best thermal performance. PMID:23389233
Relevance of Triple Coupling of Multipolar Order Parameters in URu_2Si_2
NASA Astrophysics Data System (ADS)
Koga, M.; Cox, D. L.
2000-03-01
We investigate stability of the tiny staggered magnetic dipole moment observed in URu_2Si_2, provided that an antiferroquadrupolar ordering takes place as a primary effect. A ferromagnetic octupolar ordering plays an important role in stabilizing the moment, and the stability conditions are very sensitive to the crystalline-electronic-field (CEF) energy levels of U and the RKKY couplings between the U sites. Our mean-field solution shows that the tiny dipolar ordering is hardly realized for the three lowest-lying CEF singlets proposed by Santini and Amoretti. Alternatively, we stress relevance of the non-Kramers doublets to obtain the tiny moment at low temperatures. We suggest that by combining short range quadrupolar order with the two-channel Kondo effect we can explain the magnetic susceptibility above the quadrupolar ordering temperature.
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.
T. Gopinath; Anil Kumar
2009-09-22
In this work Controlled phase shift gates are implemented on a qaudrupolar system, by using non-adiabatic geometric phases. A general procedure is given, for implementing controlled phase shift gates in an 'N' level system. The utility of such controlled phase shift gates, is demonstrated here by implementing 3-qubit Deutsch-Jozsa algorithm on a 7/2 quadrupolar nucleus oriented in a liquid crystal matrix.
NASA Astrophysics Data System (ADS)
Malave, Peter Lorenzo
Nuclear magnetic resonance in the solid state provides a wealth of inter- and intramolecular interactions that can be utilized to provide useful physical information. Chemical shift, dipolar, J-coupling, and quadrupolar interactions are all present in the solid state and provide complementary information on molecular structure and dynamics. In this work, dipolar, J-coupling, and quadrupolar interactions are studied. Lee-Goldburg off-resonance excitation is employed on a sample of 15N enriched guanosine to determine inter and intramolecular nitrogen-hydrogen distances and the scalar J-coupling constant. Satellite transition magic angle spinning is employed on an 17O enriched sample in silica to experimentally study phase cycling effects. Lee-Goldburg decoupling on guanosine is employed to determine scalar coupling in 15N bonded to 1H in guanosine. Experimental results are compared to theoretically predicted results. Results show scaling factors of 0.47 +/- 0.03 and 0.39 +/- 0.13 compared to theoretical values of 0.58. Also, a hydrogen bond shift in the resonance frequencies is postulated. Lee-Goldburg cross polarization on guanosine is used to probe inter-nuclear distances of 15N bonded to 1H in guanosine. Results are compared to x-ray crystal structures where positions of protons are energetically optimized. Simulation of experimental results is also used to compare x-ray bond lengths to Lee-Goldburg cross polarization results. The Lee-Goldburg results for N-H and N-H2 bonds show stronger agreement with simulation than x-ray results. Differences in distances range from 0.01 to 0.05 A N-H hydrogen bond distances are also compared. Finally, phase cycling effects are studied in satellite transition magic angle spinning experiments on 17O in silica. Results show that a variety of phase cycles for the final pulse in the pulse sequence can be employed to give quantitatively the same result. On the other hand, phase cycles for the first and second pulses may significantly alter the spectrum, showing more coherences for smaller numbers of phase cycles.
Baglai, Iaroslav; de Anda-Villa, Manuel; Barba-Barba, Rodrigo M; Poidevin, Corentin; Ramos-Ortíz, Gabriel; Maraval, Valérie; Lepetit, Christine; Saffon-Merceron, Nathalie; Maldonado, José-Luis; Chauvin, Remi
2015-09-28
The synthesis, crystal and electronic structures, and one- and two-photon absorption properties of two quadrupolar fluorenyl-substituted tetraphenyl carbo-benzenes are described. These all-hydrocarbon chromophores, differing in the nature of the linkers between the fluorenyl substituents and the carbo-benzene core (C?C bonds for 3?a, C?C?C?C expanders for 3?b), exhibit quasi-superimposable one-photon absorption (1PA) spectra but different two-photon absorption (2PA) cross-sections ?2PA . Z-scan measurements (under NIR femtosecond excitation) indeed showed that the C?C expansion results in an approximately twofold increase in the ?2PA value, from 336 to 656?GM (1?GM=10(-50) ?cm(4) ?s?molecule(-1) ?photon(-1) ) at ?=800?nm. The first excited states of Au and Ag symmetry accounting for 1PA and 2PA, respectively, were calculated at the TDDFT level of theory and used for sum-over-state estimations of ?2PA (?i ), in which ?i =2?hc/Ei , h is Planck's constant, c is the speed of light, and Ei is the energy of the 2PA-allowed transition. The calculated ?2PA values of 227?GM at 687?nm for 3?a and 349?GM at 708?nm for 3?b are in agreement with the Z-scan results. PMID:26267308
AN ENVELOPE DISRUPTED BY A QUADRUPOLAR OUTFLOW IN THE PRE-PLANETARY NEBULA IRAS 19475+3119
Hsu, Ming-Chien; Lee, Chin-Fei, E-mail: mchsu@asiaa.sinica.edu.tw, E-mail: cflee@asiaa.sinica.edu.tw [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China)
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.
NASA Astrophysics Data System (ADS)
Adjei-Acheamfour, Mischa; Böhmer, Roland
2014-12-01
The second-order quadrupolar broadening of the central transition of nuclear probes with half-integer spins I is demonstrated to be useful to detect ultraslow molecular motions. On the basis of density matrix calculations explicit expressions are derived for quadrupolarly modulated sin-sin and cos-cos signals of selectively excited nuclei with I = 3/2, 5/2, 7/2, and 9/2. These correlation functions are suitable for implementation in two-dimensional exchange spectroscopy as well as for stimulated-echo experiments. As an application, 17O measurements of the reorientational correlation function of water molecules in hexagonal ice are presented.
Jelinski, L W; Sullivan, C E; Batchelder, L S; Torchia, D A
1980-01-01
Collagen was labeled with [3,3,3-d3]alanine and with [d10]leucine via tissue culture. 2H nuclear magnetic resonance (NMR) spectra were obtained of collagen in solution and as fibrils using the quadrupolar echo technique. The 2H NMR data for [3,3,3-d3]alanine-labeled collagen fibrils were analyzed in terms of a model for motion in which the molecule is considered to jump between two sites, separated azimuthally by an angle 2 delta, in a time which is rapid compared with the residence time in both sites. The data suggest that the molecule undergoes reorientation over an angle, 2 delta, of approximately 30 degrees in the fibrils, and that the average angle between the alanine C alpha--C beta bond axis and the long axis of the helix is approximately 75 degrees. Reorientation is possibly segmental. The T2 for [3,3,3-d3]alanine-labeled collagen fibrils was estimated to be 105 mus. The 2H NMR data for the methyl groups of [d10]leucine-labeled collagen were analyzed qualitatively. These data established that for collagen in solution and as fibrils, rotation occurs about the leucine side-chain bonds, in addition to threefold methyl rotation and reorientation of the peptide backbone. The T2 for the methyl groups of leucine-labeled collagen is estimated to be approximately 130 mus. Taken together, these data provide strong evidence that both polypeptide backbone reorientation and amino acid side-chain motion occur in collagen molecules in the fibrils. Stabilizing interactions that determine fibril structure must therefore depend upon at least two sets of contacts in any given local region. PMID:7248459
Molecular modelling and simulation of the surface tension of real quadrupolar fluids
Stephan Werth; Katrin Stöbener; Peter Klein; Karl-Heinz Küfer; Martin Horsch; Hans Hasse
2014-08-21
Molecular modelling and simulation of the surface tension of fluids with force fields is discussed. 29 real fluids are studied, including nitrogen, oxygen, carbon dioxide, carbon monoxide, fluorine, chlorine, bromine, iodine, ethane, ethylene, acetylene, propyne, propylene, propadiene, carbon disulfide, sulfur hexafluoride, and many refrigerants. The fluids are represented by two-centre Lennard-Jones plus point quadrupole models from the literature. These models were adjusted only to experimental data of the vapour pressure and saturated liquid density so that the results for the surface tension are predictions. The deviations between the predictions and experimental data for the surface tension are of the order of 20 percent. The surface tension is usually overestimated by the models. For further improvements, data on the surface tension can be included in the model development. A suitable strategy for this is multi-criteria optimization based on Pareto sets. This is demonstrated using the model for carbon dioxide as an example.
Unusual anisotropic magnetoresistance in charge-orbital ordered Nd0.5Sr0.5MnO3 polycrystals
NASA Astrophysics Data System (ADS)
Yang, Huali; Wang, Baomin; Liu, Yiwei; Yang, Zhihuan; Zhu, Xiaojian; Xie, Yali; Zuo, Zhenghu; Chen, Bin; Zhan, Qingfeng; Wang, Junling; Li, Run-Wei
2014-12-01
Due to its potential application in magnetic recording and sensing technologies, the anisotropic magnetoresistance (AMR) effect has attracted lasting attention. Despite the long history, AMR effect has not been fully understood especially in the unconventional materials, such as perovskite manganites. Here, we report an unusual AMR effect in the charge-orbital ordered (COO) Nd0.5Sr0.5MnO3 polycrystals, which is observed when the magnetic field rotates in the plane that is perpendicular to the current (out-of-plane AMR). Despite being a polycrystalline sample where no anisotropy is expected, the resistivity shows a large irreversible drop with rotating magnetic field. A model has been proposed based on anisotropic magnetic field induced the melting of COO phase to explain the unusual out-of-plane AMR successfully. Our results demonstrate a new way for understanding the close relationship between phase separation and AMR effect in COO manganites.
Measurements of the magnetic field induced by a turbulent flow of liquid metal
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.
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.
Çelik, Mustafa Salih; Güven, Kemal; Akpolat, Veysi; Akda?, Mehmet Zulkuf; Naz?ro?lu, Mustafa; Gül-Güven, Reyhan; Çelik, M Yusuf; Erdo?an, 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
Extremely Low Frequency Magnetic Fields Induce Spermatogenic Germ Cell Apoptosis: Possible Mechanism
Lee, Sang-Kon; Park, Sungman; Gimm, Yoon-Myoung; Kim, Yoon-Won
2014-01-01
The energy generated by an extremely low frequency electromagnetic field (ELF-EMF) is too weak to directly induce genotoxicity. However, it is reported that an extremely low frequency magnetic field (ELF-MF) is related to DNA strand breakage and apoptosis. The testes that conduct spermatogenesis through a dynamic cellular process involving meiosis and mitosis seem vulnerable to external stress such as heat, MF exposure, and chemical or physical agents. Nevertheless the results regarding adverse effects of ELF-EMF on human or animal reproductive functions are inconclusive. According to the guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP; 2010) for limiting exposure to time-varying MF (1?Hz to 100?kHz), overall conclusion of epidemiologic studies has not consistently shown an association between human adverse reproductive outcomes and maternal or paternal exposure to low frequency fields. In animal studies there is no compelling evidence of causal relationship between prenatal development and ELF-MF exposure. However there is increasing evidence that EL-EMF exposure is involved with germ cell apoptosis in testes. Biophysical mechanism by which ELF-MF induces germ cell apoptosis has not been established. This review proposes the possible mechanism of germ cell apoptosis in testes induced by ELF-MF. PMID:25025060
Xi Yang; Andrew Beckwith
2004-09-02
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.
Axion emission by magnetic-field induced conversion of longitudinal plasmons
N. V. Mikheev; L. A. Vassilevskaya
1998-01-01
Magnetic fields mix axions with photons, allowing for the cyclotron process e\\u000a-> e + a by virtue of an intermediate plasmon even if axions do not couple to\\u000aelectrons at tree level. The axion and longitudinal-plasmon dispersion\\u000arelations always cross for a certain wave number, leading to a resonant\\u000aenhancement of this process. Even then, however, it cannot quite
Axion emission by magnetic-field induced conversion of longitudinal plasmons
N. V. Mikheev; G. Raffelt; L. A. Vassilevskaya
1998-01-01
Magnetic fields mix axions with photons, allowing for the cyclotron process e--->e-a by virtue of an intermediate plasmon even if axions do not couple to electrons at the tree level. The axion and longitudinal-plasmon dispersion relations always cross for a certain wave number, leading to a resonant enhancement of this process. Even then, however, it cannot quite compete with the
Basaran, Burak
2011-02-22
Magnetic Shape Memory Alloys (MSMAs) combine shape-change/deformationrecovery abilities of heat driven conventional shape memory alloys (SMA) and magnetic field driven magnetostrictives through martensitic transformation. They are promising...
Lee, Sang-Kon; Park, Sungman; Gimm, Yoon-Myoung; Kim, Yoon-Won
2014-01-01
The energy generated by an extremely low frequency electromagnetic field (ELF-EMF) is too weak to directly induce genotoxicity. However, it is reported that an extremely low frequency magnetic field (ELF-MF) is related to DNA strand breakage and apoptosis. The testes that conduct spermatogenesis through a dynamic cellular process involving meiosis and mitosis seem vulnerable to external stress such as heat, MF exposure, and chemical or physical agents. Nevertheless the results regarding adverse effects of ELF-EMF on human or animal reproductive functions are inconclusive. According to the guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP; 2010) for limiting exposure to time-varying MF (1?Hz to 100?kHz), overall conclusion of epidemiologic studies has not consistently shown an association between human adverse reproductive outcomes and maternal or paternal exposure to low frequency fields. In animal studies there is no compelling evidence of causal relationship between prenatal development and ELF-MF exposure. However there is increasing evidence that EL-EMF exposure is involved with germ cell apoptosis in testes. Biophysical mechanism by which ELF-MF induces germ cell apoptosis has not been established. This review proposes the possible mechanism of germ cell apoptosis in testes induced by ELF-MF. PMID:25025060
Structure of the photon and magnetic field induced birefringence and dichroism
Juan Alberto Beswick; Carlo Rizzo
2007-02-13
In this letter we show that the dichroism and ellipticity induced on a linear polarized light beam by the presence of a magnetic field in vacuum can be explained in the framework of the de Broglie's fusion model of a photon. In this model it is assumed that the usual photon is the spin 1 state of a particle-antiparticle bound state of two spin 1/2 fermions. The other S=0 state is referred to as the \\emph{second} photon. On the other hand, since no charged particle neither particles having an electric dipole are considered, no effect is predicted in the presence of electric fields and this model is not in contradiction with star cooling data or solar axion search.
Structure of the photon and magnetic field induced birefringence and dichroism
Beswick, J A; Beswick, Juan Alberto; Rizzo, Carlo
2007-01-01
In this letter we show that the dichroism and ellipticity induced on a linear polarized light beam by the presence of a magnetic field in vacuum can be explained in the framework of the de Broglie's fusion model of a photon. In this model it is assumed that the usual photon is the spin 1 state of a particle-antiparticle bound state of two spin 1/2 fermions. The other S=0 state is referred to as the \\emph{second} photon. On the other hand, since no charged particle neither particles having an electric dipole are considered, no effect is predicted in the presence of electric fields and this model is not in contradiction with star cooling data or solar axion search.
Luderer, A.A. (Corning Glass Works, Corning, NY); Borrelli, N.F.; Panzarino, J.N.; Mansfield, G.R.; Hess, D.M.; Brown, J.L.; Barnett, E.H.; Hahn, E.W.
1983-04-01
Hyperthermia has found to be a useful modality for cancer therapy. In this report, a biocompatible, ferrimagnetic glass-ceramic capable of inducing localized hyperthermia by hysteresis heating upon exposure to an alternating magnetic field is presented. When the glass-ceramic was placed in the region of a subcutaneously transplanted, weakly antigenic breast carcinoma and subjected to the magnetic field, sufficient temperature rise was obtained to cause significant (approx.50%) tumor regrowth delay and a 12% permanent control. The data demonstrate that glass-ceramic-mediated hysteresis heating may be a useful therapeutic approach in the treatment of cancer which offers the advantage of producing a highly localized and predictable tumor volume hyperthermia.
Magnetic field-induced reversible variant rearrangement in FePd single crystals
Taya, Minoru
field is required for the phase change to take for both Ni 1359-6454/$30.00 Ó 2004 Acta Materialia Inc variant rearrangement and (iii) hybrid mechanism. The first mechanism is based on the phase change from.8% was also observed when the specimen was compressed. Ó 2004 Acta Materialia Inc. Published by Elsevier Ltd
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.
Vacuum current and magnetic field induced by an impenetrable flux tube. Dirichlet problem
Volodymyr M. Gorkavenko; Iryna V. Ivanchenko
2015-05-10
We consider the vacuum polarization effects created by a finite radius magnetic-flux-carrying tube that is impenetrable for quantum matter. The vacuum polarization depends on the choice of a boundary condition at the edge of the tube. We impose a perfectly reflecting (Dirichlet) boundary condition at the edge of the tube on the charged massive scalar matter field which is quantized outside the tube. We find that a current is induced in the vacuum of the quantized scalar field and it circulates around the tube. As a consequence of the Maxwell equation, a magnetic field strength is also induced in the vacuum and is directed along the tube. We restrict our consideration to a plane case. The behavior of the current and the field strength is comprehensively analyzed. In contrast to the model of singular magnetic filament, magnetic field strength is finite at the edge of the string. Induced vacuum effects strongly depend on the tube radius $r_0$. They are quite negligible at $mr_0 > 1$, whereas it becomes noticeable at $mr_0\\ll1$. Induced vacuum effects are less than in the case of singular magnetic filament.
Magnetic field-induced gluonic (inverse) catalysis and pressure (an)isotropy in QCD
NASA Astrophysics Data System (ADS)
Bali, G. S.; Bruckmann, F.; Endr?di, G.; Gruber, F.; Schäfer, A.
2013-04-01
We study the influence of strong external magnetic fields on gluonic and fermionic observables in the QCD vacuum at zero and nonzero temperatures, via lattice simulations with N f = 1 + 1 + 1 staggered quarks of physical masses. The gluonic action density is found to undergo magnetic catalysis at low temperatures and inverse magnetic catalysis near and above the transition temperature, similar to the quark condensate. Moreover, the gluonic action develops an anisotropy: the chromo-magnetic field parallel to the external field is enhanced, while the chromo-electric field in this direction is suppressed. We demonstrate that the same hierarchy is obtained using the Euler-Heisenberg effective action. Conversely, the topological charge density correlator does not reveal a significant anisotropy up to magnetic fields eB ? 1 GeV2. Furthermore, we show that the pressure remains isotropic even for nonzero magnetic fields, if it is defined through a compression of the system at fixed external field. In contrast, if the flux of the field is kept fixed during the compression — which is the situation realized in the lattice simulation — the pressure develops an anisotropy. We estimate the quark and gluonic contributions to this anisotropy, and relate them to the magnetization of the QCD vacuum. After performing electric charge renormalization, we obtain an estimate for the magnetization, which indicates that QCD is paramagnetic.
Particle size and magnetic field-induced optical properties of magnetic fluid nanoparticles.
Rao, G Narsinga; Yao, Y D; Chen, Y L; Wu, K T; Chen, J W
2005-09-01
Magnetite nanoparticles with diameters of 7, 9, and 12 nm have been prepared by a chemical coprecipitation method. The transmission of light through magnetic fluid containing these nanoparticles has been investigated as a function of film thickness with wavelength between 400 and 750 nm, and applied magnetic fields up to 275 Oe. The transmission threshold shifts to the lower wavelength side with decreasing magnetic fluid film thickness as well as the particle size. For a given film thickness, the transmittance increases with increasing magnetic field for films with a particle size of 7 and 9 nm, but decreases in the 12-nm film. This is attributed to the competition between the van der Waals and dipole-dipole interaction. PMID:16241436
Biomaterials 28 (2007) 11051114 Flow and magnetic field induced collagen alignment
Kaufman, Laura
2007-01-01
that are several millimeters thick. r 2006 Elsevier Ltd. All rights reserved. Keywords: Collagen; Confocal, which vary in the length of helix and nature and size of the non-helical portions, exist in animal and supports animal cells. Type I collagen is the predominant form of collagen in animal tissue and is found
Lindemuth, Irvin R.; Siemon, Richard E.; Bauer, Bruno S.; Angelova, Milena A.; Atchison, Walter L. [University of Nevada, Reno, Nevada (United States); Los Alamos National Laboratory, Los Alamos, New Mexico (United States)
2010-11-05
Numerical simulations of experiments in which plasma is formed on an aluminum surface by megagauss magnetic fields provide the first computational demonstration of a magnetic-field threshold that must be reached for aluminum plasma to begin to form. The computed times of plasma initiation agree reasonably well with the observations across the full range of rod diameters, leading to the conclusion that plasma formation is a thermal process. Computationally, plasma forms first in low-density material that is resistive enough to expand across the magnetic field and yet conductive enough that Ohmic heating exceeds expansion cooling.
Magnetic-field-induced enhancement of atomic stabilization in intense high-frequency laser fields
NASA Astrophysics Data System (ADS)
Simonsen, Aleksander Skjerlie; Førre, 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 Schrödinger 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.
X?CT analysis of magnetic field-induced phase transitions in magnetorheological elastomers
NASA Astrophysics Data System (ADS)
Borbáth, T.; Günther, S.; Borin, D. Yu; Gundermann, Th; Odenbach, S.
2012-10-01
The phase behavior of polymer solutions and composites is a complex issue and is of both technological and fundamental interest. For a better understanding of the microstructure formation in magnetorheological (MR) elastomers, x-ray micro-computed tomography (X?CT) investigations were carried out. Magnetorheological elastomers with 5% mass content of iron powder were prepared under different magnetic field strengths between 1 and 220 kA m-1. Through quantitative analysis, valuable information was obtained regarding the number, size and frequency distribution of column structures in MR elastomers, as well as the magnetic field required to force structure formation.
Magnetic-field-induced tunneling and minigap transport in double quantum wells
Lyo, S.K.; Simmons, J.A.; Harff, N.E.; Eiles, T.M.; Klem, J.F.
1995-08-01
We review recent theoretical and experimental results on low- temperature tunneling and in-plane transport properties in double quantum wells (DQWs) in an in-plane magnetic field B{parallel}. These properties arise from combined effect of B{parallel}-induced relative displacement of the wave vectors in the two QWs and the interwell tunneling. In weakly coupled DQWs, the tunneling conductance has two sharp maxima as a function of B{parallel}. In strongly coupled DQWs, a partial minigap is formed due to anticrossing of the two QW dispersion curves, yielding sharp B{parallel}-dependent structures in the density of states and in- plane transport properties. Excellent agreement is obtained between theory and data from GaAs/AlGaAs DQWs.
Magnetic field induced discontinuous spin reorientation in ErFeO3 single crystal
NASA Astrophysics Data System (ADS)
Shen, Hui; Cheng, Zhenxiang; Hong, Fang; Xu, Jiayue; Yuan, Shujuan; Cao, Shixun; Wang, Xiaolin
2013-11-01
The spin reorientation of ErFeO3 that spontaneously occurs at low temperature has been previously determined to be a process involving the continuous rotation of Fe3+ spins. In this work, the dynamic process of spin reorientation in ErFeO3 single crystal has been investigated by AC susceptibility measurements at various frequencies and static magnetic fields. Interestingly, two completely discontinuous steps are induced by a relatively large static magnetic field due to the variation in the magnetic anisotropy during this process. It provides deeper insights into the intriguing magnetic exchange interactions which dominate the sophisticated magnetic phase transitions in the orthoferrite systems.
Magnetic field-induced quantum criticality via new asymptotically AdS5 solutions
NASA Astrophysics Data System (ADS)
D'Hoker, Eric; Kraus, Per
2010-11-01
Using analytical methods, we derive and extend previously obtained numerical results on the low temperature properties of holographic duals to four-dimensional gauge theories at finite density in a nonzero magnetic field. We find a new asymptotically AdS5 solution representing the system at zero temperature. This solution has vanishing entropy density, and the charge density in the bulk is carried entirely by fluxes. The dimensionless magnetic field to charge density ratio for these solutions is bounded from below, with a quantum critical point appearing at the lower bound. Using matched asymptotic expansions, we extract the low temperature thermodynamics of the system. Above the critical magnetic field, the low temperature entropy density takes a simple form, linear in the temperature, and with a specific heat coefficient diverging at the critical point. At the critical magnetic field, we derive the scaling law s ~ T1/3 inferred previously from the numerical analysis. We also compute the full scaling function describing the region near the critical point and identify the dynamical critical exponent: z = 3. These solutions are expected to holographically represent boundary theories in which strongly interacting fermions are filling up a Fermi sea. They are fully top-down constructions in which both the bulk and boundary theories have well-known embeddings in the string theory. Communicated by S F Ross
Novel magnetic-field-induced minigap and transport in coupled double quantum wells
Lyo, S.K.; Simmons, J.A.; Harff, N.E.; Klem, J.F.
1995-08-01
A review is given of recent theoretical and experimental work on in-plane electron transport in strongly coupled double quantum wells (QWs) in the presence of an in-plane magnetic field B{sub {parallel}} {parallel} x. This system displays unusual electronic and transport properties arising from a partial minigap ({approximately} a few meV) formed in the transverse in-plane direction k{sub y} {perpendicular} B{sub {parallel}} in k-space due to the anticrossing of the two QW dispersion curves displaced relative to each other by {Delta}k{sub y} {proportional_to} B{sub {parallel}}. Sweeping B{sub {parallel}} moves the minigap through the Fermi level ({mu}), deforming the Fermi surface from a two-component surface (with one orbit inside the other) to a single-orbit surface, and then back to a two-separated-orbit structure, accordingly as {mu} lies above, inside, and below the gap, respectively. The authors show that the density of states develops a sharp van Hove singularity at the lower gap edge, while transport properties such as the in-plane conductance and the cyclotron mass show sharp B{sub {parallel}}-dependent structures as {mu} passes through the gap edges.
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 (« less
Magnetic field induced discontinuous spin reorientation in ErFeO{sub 3} single crystal
Shen, Hui [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China) [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2500 (Australia); Cheng, Zhenxiang, E-mail: cheng@uow.edu.au; Hong, Fang; Wang, Xiaolin [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2500 (Australia)] [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2500 (Australia); Xu, Jiayue [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China)] [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Yuan, Shujuan; Cao, Shixun [Department of Physics, Shanghai University, Shanghai 200444 (China)] [Department of Physics, Shanghai University, Shanghai 200444 (China)
2013-11-04
The spin reorientation of ErFeO{sub 3} that spontaneously occurs at low temperature has been previously determined to be a process involving the continuous rotation of Fe{sup 3+} spins. In this work, the dynamic process of spin reorientation in ErFeO{sub 3} single crystal has been investigated by AC susceptibility measurements at various frequencies and static magnetic fields. Interestingly, two completely discontinuous steps are induced by a relatively large static magnetic field due to the variation in the magnetic anisotropy during this process. It provides deeper insights into the intriguing magnetic exchange interactions which dominate the sophisticated magnetic phase transitions in the orthoferrite systems.
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.
Andreas Jordan; Regina Scholz; Peter Wust; Horst Fähling; Roland Felix
1999-01-01
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
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.
Magnetic Field-induced Effects in Photon Scattering and Absorption by Crystals
NASA Astrophysics Data System (ADS)
Lovesey, Stephen William; Balcar, Ewald
2011-06-01
Electrons respond in a variety of ways to a steady magnetic field, and bulk material properties include helicon waves, Faraday rotation of the plane of polarization of photons and many other magneto-optic effects. Information about electrons at an atomic level of detail is obtained from Bragg diffraction, and diffraction enhanced by an atomic resonance provides information not available by any other technique in the science of materials, e.g., the direct observation of magnetic charge and anapoles. We formulate resonant Bragg diffraction from crystalline materials subject to a steady magnetic field. By way of illustration of our general findings for field-induced effects in diffraction enhanced by E1--E1 and E1--M1 resonances, we calculate unit-cell structure factors for diffraction from multiferroic gallium ferrate and anti-ferromagnetic copper oxide. In addition, we provide expressions for frequency-integrated dichroic signals conjugate to standard magneto-optic effects, such as Faraday rotation.
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.
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.
Faucher, Alexandra; Terskikh, Victor V; Wasylishen, Roderick E
2015-07-01
Solid-state (11)B NMR measurements of Lewis acid-base adducts of the form R3AsBR'3 (R = Me, Et, Ph; R' = H, Ph, C6F5) were carried out at several magnetic field strengths (e.g., B0 = 21.14, 11.75, and 7.05 T). The (11)B NMR spectra of these adducts exhibit residual dipolar coupling under MAS conditions, allowing for the determination of effective dipolar coupling constants, Reff((75)As,(11)B), as well as the sign of the (75)As nuclear quadrupolar coupling constants. Values of Reff((75)As,(11)B) range from 500 to 700 Hz. Small isotropic J-couplings are resolved in some cases, and the sign of (1)J((75)As,(11)B) is determined. Values of CQ((75)As) measured at B0 = 21.14 T for these triarylborane Lewis acid-base adducts range from -82 ± 2 MHz for Et3AsB(C6F5)3 to -146 ± 1 MHz for Ph3AsBPh3. For Ph3AsBH3, two crystallographically nonequivalent sites are identified with CQ((75)As) values of -153 and -151 ± 1 MHz. For the uncoordinated Lewis base, Ph3As, four (75)As sites with CQ((75)As) values ranging from 193.5 to 194.4 ± 2 MHz are identified. At these applied magnetic field strengths, the (75)As quadrupolar interaction does not satisfy high-field approximation criteria, and thus, an exact treatment was used to describe this interaction in (11)B and (75)As NMR spectral simulations. NMR parameters calculated using the ADF and CASTEP program packages support the experimentally derived parameters in both magnitude and sign. These experiments add to the limited body of literature on solid-state (75)As NMR spectroscopy and serve as examples of spin-spin-coupled quadrupolar spin pairs, which are also rarely treated in the literature. PMID:26075575
NASA Astrophysics Data System (ADS)
Rusz, Ján; Oppeneer, Peter M.; Curro, Nicholas J.; Urbano, Ricardo R.; Young, Ben-Li; Lebègue, S.; Pagliuso, Pascoal G.; Pham, Long D.; Bauer, Eric D.; Sarrao, John L.; Fisk, Zachary
2008-06-01
We report calculations of the electric-field gradients (EFGs) in pure and doped CeMIn5 ( M=Co , Rh, and Ir) compounds and compare with experiment. The degree to which the Ce4f electron is localized is treated within various models: the local-density approximation, generalized gradient approximation (GGA), GGA+U , and 4f -core approaches. We find that there is a correlation between the observed EFG and whether the 4f electron participates in the band formation or not. We also find that the EFG evolves linearly with Sn doping in CeRhIn5 , suggesting the electronic structure is modified by doping. In contrast, the observed EFG in CeCoIn5 doped with Cd changes little with doping. These results indicate that nuclear quadrupolar resonance is a sensitive probe of electronic structure.
Hayashi, Hisashi; Kawata, Masaki; Sato, Atsushi; Udagawa, Yasuo; Inami, Toshiya; Ishii, Kenji; Ogasawara, Haruhiko; Nanao, Susumu [IMRAM, Tohoku University, Katahira 2-1-1, Sendai 980-8577, Japan and PRESTO, JST, 4-1-8 Honcho Kawaguchi, Saitama, 332-0012 (Japan); SRRC, JAERI, Mikazuki, Hyogo, 679-5148 (Japan); Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States) and APS, Argonne National Laboratory, 9700, South Cass Avenue, Illinois 60439 (United States); IIS, University of Tokyo, Komaba 4-6-1, Meguro, Tokyo 153-8505 (Japan)
2005-07-15
The 2p3d resonant inelastic x-ray-scattering spectra of Ho{sub 2}O{sub 3} are measured under 0.7 eV resolution and analyzed in terms of an equation based on the Kramers-Heisenberg formula. Broadening due to core-hole lifetime (4.26 eV) is completely suppressed to give sharp absorption bands with width of <0.5 eV together with energy position uncertainty {approx}0.3 eV. Observed bands are assigned to be well-known 2p{yields}4f quadrupolar transitions that are otherwise buried under lifetime-broadened intense 2p{yields}5d dipole transition. The present work opens up an opportunity to study 4f-5d interactions more accurately.
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 ?T) 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.
Barrow, Nathan S; Yates, Jonathan R; Feller, Steven A; Holland, Diane; Ashbrook, Sharon E; Hodgkinson, Paul; Brown, Steven P
2011-04-01
Magic-angle spinning (MAS) NMR spin-echo dephasing is systematically investigated for the spin I = 3/2 (11)B nucleus in lithium diborate, Li(2)O·2B(2)O(3). A clear dependence on the quadrupolar frequency (?(Q)(PAS)/2? = 3C(Q)/[4I(2I- 1)]) is observed: the B3 (larger C(Q)) site dephases more slowly than the B4 site at all investigated MAS frequencies (5 to 20 kHz) at 14.1 T. Increasing the MAS frequency leads to markedly slower dephasing for the B3 site, while there is a much less evident effect for the B4 site. Considering samples at 5, 25, 80 (natural abundance) and 100% (11)B isotopic abundance, dephasing becomes faster for both sites as the (11)B isotopic abundance increases. The experimental behaviour is rationalised using density matrix simulations for two and three dipolar-coupled (11)B nuclei. The experimentally observed slower dephasing for the larger C(Q) (B3) site is reproduced in all simulations and is explained by the reintroduction of the dipolar coupling by the so-called "spontaneous quadrupolar-driven recoupling mechanism" having a different dependence on the MAS frequency for different quadrupolar frequencies. Specifically, isolated spin-pair simulations show that the spontaneous quadrupolar-driven recoupling mechanism is most efficient when the quadrupolar frequency is equal to twice the MAS frequency. While for isolated spin-pair simulations, increasing the MAS frequency leads to faster dephasing, agreement with experiment is observed for three-spin simulations which additionally include the homogeneous nature of the homonuclear dipolar coupling network. First-principles calculations, using the GIPAW approach, of the (2)J(11B-11B) couplings in lithium diborate, metaborate and triborate are presented: a clear trend is revealed whereby the (2)J(11B-11B) couplings increase with increasing B-O-B bond angle and B-B distance. However, the calculated (2)J(11B-11B) couplings are small (0.95, 1.20 and 2.65 Hz in lithium diborate), thus explaining why no zero crossing due to J modulation is observed experimentally, even for the sample at 25% (11)B where significant spin-echo intensity remains out to durations of ?200 ms. PMID:21321719
Heavy-fermion superconductivity in the quadrupole ordered state of PrV2Al20.
Tsujimoto, Masaki; Matsumoto, Yosuke; Tomita, Takahiro; Sakai, Akito; Nakatsuji, Satoru
2014-12-31
PrV2Al20 is a rare example of a heavy-fermion system based on strong hybridization between conduction electrons and nonmagnetic quadrupolar moments of the cubic ?3 ground doublet. Here, we report that a high-quality single crystal of PrV2Al20 exhibits superconductivity at Tc=50??mK in the antiferroquadrupole-ordered state under ambient pressure. The heavy-fermion character of the superconductivity is evident from the specific heat jump of ?C/T?0.3??J/mol?K(2) and the effective mass m*/m0?140 estimated from the temperature dependence of the upper critical field. Furthermore, the high-quality single crystals exhibit double transitions at TQ=0.75??K and T*=0.65??K associated with quadrupole and octupole degrees of freedom of the ?3 doublet. In the ordered state, the specific heat C/T shows a T(3) dependence, indicating the gapless mode associated with the quadrupole order, the octupole order, or both. The strong sensitivity to impurity of the superconductivity suggests unconventional character due to significant quadrupolar fluctuations. PMID:25615375
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
Wang, Bing; Wang, Yaochuan; Hua, Jianli; Jiang, Yihua; Huang, Jinhai; Qian, Shixiong; Tian, He
2011-02-25
In this work, we have developed a new class of aggregation-induced emission (AIE) active compounds, in which three electron-donating diphenylamine, phenothiazine, or carbazole groups are connected to the 1, 4-positions of the benzene through bis(?-cyano-4-diphenylaminostyryl) conjugation bridges to form three triarylamine quadrupolar derivatives (3?a-c). Their one- and two-photon absorption properties have been investigated. The two-photon absorption (2PA) cross sections measured by the open-aperture Z-scan technique were determined to be 1016, 1484, and 814?GM for 3?a-c, respectively. From this result, the high 2PA properties of these molecules are attributed to the extended ? system and enhanced intramolecular charge transfer from the starburst triarylamine to the cyano group. Moreover, cyano-substituted diphenylamine styrylbenzene (CNDPASB)-based compounds are very weakly fluorescent in THF, but their intensities increase by almost 230, 70, and 5 times, respectively, in water/THF (v/v 90?%) mixtures, in which they exhibit strongly enhanced red, orange, and deep yellow fluorescence emissions, respectively. This result indicates that the intramolecular vibration and rotation of these dyes is considerably restricted in nano-aggregates formed in water, leading to significant increases in fluorescence. It was found that the color tuning of the CNDPASB-based compounds could be conveniently accomplished by changing the starburst triarylamine donor moiety. Multilayer electroluminescence devices with TPBI (2,2',2''-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole)) electron-transporting layers have been made, with 3?a and 3?c as a non-doping red-yellow emitter. The preliminary results for these multilayer devices show a maximum efficiency of 0.25?%, and electroluminescence (EL) wavelengths around 568?nm. The excellent 2PA and AIE properties of these compounds make them potential materials for biophotonic applications. PMID:21264969
Topcu, Suat; Nasser, Jamil; Daku, Latevi Max Lawson; Fritzsche, Stephan
2006-04-15
Frequency shifts of the Ag I 4d{sup 10}5s {sup 2}S{sub 1/2}(F=0,M{sub F}=0) to 4d{sup 9}5s{sup 2} {sup 2}D{sub 5/2}(F{sup '}=2,M{sub F{sup '}}=0) electric-quadrupole transition at 330.6 nm due to external fields are calculated using multiconfigurational self-consistent field methods. As this forbidden transition is free from first order Doppler and Zeeman effects, it is under investigation for the realization of an atomic optical clock. The calculated perturbations are the light shift, the blackbody frequency shift, and the quadratic Zeeman shift. Results show that a total uncertainty of 10{sup -18} could be reach without confining the atoms in a Lamb-Dicke regime in an optical lattice.
Specific heat and entropy change at the first order phase transition of La(Fe-Mn-Si)13-H compounds
NASA Astrophysics Data System (ADS)
Basso, Vittorio; Küpferling, Michaela; Curcio, Carmen; Bennati, Cecilia; Barzca, Alexander; Katter, Matthias; Bratko, Milan; Lovell, Edmund; Turcaud, Jeremy; Cohen, Lesley F.
2015-08-01
In this paper, we present the results of an experimental investigation on the magnetocaloric properties of hydrogenated La(Fe-Mn-Si)13-H with Mn substituting Fe to finely tune the transition temperature. We measured the specific heat under magnetic field cp(H, T) and the magnetic field induced isothermal entropy change ?s(H, T) of a series of compounds by direct Peltier calorimetry. Results show that increasing Mn from 0.06 to 0.46 reduces the transition temperature from 339 K to 270 K whilst the total entropy change due to a 1.5 T field is depressed from 18.7 J kg-1 K-1 to 10.2 J kg-1 K-1 and the thermal hysteresis similarly is reduced from 1.5 K to zero. In the paper, we interpret the results in terms of a magnetic phase transition changing from the first to the second order with increasing Mn content, and we discuss the value of the results for magnetic cooling applications.
Ab initio theory of magnetic-field-induced odd-frequency two-band superconductivity in MgB2
NASA Astrophysics Data System (ADS)
Aperis, Alex; Maldonado, Pablo; Oppeneer, Peter M.
2015-08-01
We develop the anisotropic Eliashberg framework for superconductivity in the presence of an applied magnetic field. Using as input the ab initio calculated electron and phonon band structures and electron-phonon coupling, we solve self-consistently the anisotropic Eliashberg equations for the archetypal superconductor MgB2. We find two self-consistent solutions, time-even two-band superconductivity, as well as unconventional time-odd s -wave spin triplet two-band superconductivity emerging with applied field. We provide the full momentum, frequency, and spin-resolved dependence and magnetic field-temperature phase diagrams of the time-even and time-odd superconducting pair amplitudes and predict fingerprints of this novel odd-frequency state in tunneling experiments.
Kumlin, Timo; Heikkinen, Päivi; Laitinen, Jarmo T; Juutilainen, Jukka
2005-09-01
The effect of magnetic field (MF) exposure on melatonin production was studied in female CD(2)F(1)(BALB/c x DBA/2) mice. The mice were exposed to a 50 Hz MF at 100 microT for 52 days and nocturnal urine was collected 1, 3, 7, 14, 16 and 23 days after the beginning of MF exposure. The animal room was illuminated for 12 h daily at 200 lux. To study the circadian rhythm of melatonin production, night and day samples of urine were collected once, at about 40 days after the beginning of MF exposure. Urinary 6-hydroxy melatonin sulfate (6-OHMS) was determined to assess melatonin production. The pineal glands were analyzed for melatonin content at the middle of the dark period. No statistically significant peak of melatonin was observed in either group. The light-regulated natural melatonin rhythm was absent in sham-exposed mice. The MF exposure caused a significant day-night difference in the 6-OHMS levels, but did not affect the total excretion of 6-OHMS during the 24-hour period. A possible interpretation of the findings is that MF exposure increases the sensitivity of the pineal gland to light in this strain normally insensitive to the circadian light variations. Further studies on interaction of light and MF exposure might help in understanding the inconsistencies of earlier research on MFs and melatonin. PMID:16210787
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...
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.
Raaijmakers, A J E; Raaymakers, B W; Lagendijk, J J W
2008-02-21
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. PMID:18263948
Magnetic-Field-Induced Condensation of Triplons in Han Purple Pigment BaCuSi2O6
NASA Astrophysics Data System (ADS)
Jaime, M.; Correa, V. F.; Harrison, N.; Batista, C. D.; Kawashima, N.; Kazuma, Y.; Jorge, G. A.; Stern, R.; Heinmaa, I.; Zvyagin, S. A.; Sasago, Y.; Uchinokura, K.
2004-08-01
Besides being an ancient pigment, BaCuSi2O6 is a quasi-2D magnetic insulator with a gapped spin dimer ground state. The application of strong magnetic fields closes this gap, creating a gas of bosonic spin triplet excitations. The topology of the spin lattice makes BaCuSi2O6 an ideal candidate for studying the Bose-Einstein condensation of triplet excitations as a function of the external magnetic field, which acts as a chemical potential. In agreement with quantum Monte Carlo numerical simulations, we observe a distinct lambda anomaly in the specific heat together with a maximum in the magnetic susceptibility upon cooling down to liquid helium temperatures.
Rauš, Snežana; Selakovi?, Vesna; Radenovi?, Lidija; Proli?, Zlatko; Jana?, Branka
2012-03-17
The purpose of this study was to evaluate behavioural effects of an extremely low frequency magnetic field (ELF-MF) in 3-month-old Mongolian gerbils submitted to global cerebral ischemia. After 10-min occlusion of both common carotid arteries, the gerbils were placed in the vicinity of an electromagnet and continuously exposed to ELF-MF (50Hz, 0.5mT) for 7 days. Their behaviour (locomotion, stereotypy, rotations, and immobility) was monitored on days 1, 2, 4, 7, and 14 after reperfusion for 60min in the open field. It was shown that the 10-min global cerebral ischemia per se induced a significant motor activity increase (locomotion, stereotypy and rotations), and consequently immobility decrease until day 4 after reperfusion, compared to control gerbils. Exposure to ELF-MF inhibited development of ischemia-induced motor hyperactivity during the whole period of registration, but significantly in the first 2 days after reperfusion, when the postischemic hyperactivity was most evident. Motor activity of these gerbils was still significantly increased compared to control ones, but only on day 1 after reperfusion. Our results revealed that the applied ELF-MF (50Hz, 0.5mT) decreased motor hyperactivity induced by the 10-min global cerebral ischemia, via modulation of the processes that underlie this behavioural response. PMID:22119248
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 ?m to 50 ?m 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.
Singh, Sunil K; Kumar, Kaushal; Srivastava, Manish K; Rai, Devendra K; Rai, Shyam B
2010-05-15
The effect of an external magnetic field (0-1 T) on the upconversion emission (lambda(exc)=976 nm) of Gd(2)O(3):Er(3+)Yb(3+) nanocrystalline phosphor has been studied. Optical bistability (hysteresis behavior in the intensity of the optical emission) for different transitions of the Er(3+) ion has been observed for a complete cycle of the magnetic field between 0 and 1 T. The phosphor shows paramagnetic behavior, consistent with the presence of Gd(3+) ions, at room temperature. Interaction between induced magnetization in the Gd(2)O(3) host and the intrinsic magnetic moment of the nanosized clusters of Er(3+) and Yb(3+) ion pairs is proposed to be responsible for the hysteresis behavior. PMID:20479813
2015-01-01
Iron–dextran nanoparticles functionalized with T cell activating proteins have been used to study T cell receptor (TCR) signaling. However, nanoparticle triggering of membrane receptors is poorly understood and may be sensitive to physiologically regulated changes in TCR clustering that occur after T cell activation. Nano-aAPC bound 2-fold more TCR on activated T cells, which have clustered TCR, than on naive T cells, resulting in a lower threshold for activation. To enhance T cell activation, a magnetic field was used to drive aggregation of paramagnetic nano-aAPC, resulting in a doubling of TCR cluster size and increased T cell expansion in vitro and after adoptive transfer in vivo. T cells activated by nano-aAPC in a magnetic field inhibited growth of B16 melanoma, showing that this novel approach, using magnetic field-enhanced nano-aAPC stimulation, can generate large numbers of activated antigen-specific T cells and has clinically relevant applications for adoptive immunotherapy. PMID:24564881
Ming Jun Hu; Bin Lin; Shu Hong Yu
2008-01-01
One-dimensional magnetic Ni-Co alloy microwires with different microstructures and differently shaped building blocks including\\u000a spherical particles, multilayer stacked alloy plates, and alloy flowers, have been synthesized by an external magnetic field-assisted\\u000a solvothermal reaction of mixtures of cobalt(II) chloride and nickel(II) chloride in 1, 2-propanediol with different NaOH concentrations.\\u000a By adjusting the experimental parameters, such as precursor concentration and Ni\\/Co ratio,
Magnetic field-induced spontaneous polarization reversal in multiferroic Mn0.85Co0.15WO4
NASA Astrophysics Data System (ADS)
Poudel, N.; Liang, K.-C.; Wang, Y. Q.; Sun, Y. Y.; Lorenz, B.; Ye, F.; Fernandez-Baca, J. A.; Chu, C. W.
2014-03-01
In this work, we report the effect of c-axis magnetic field in magnetic and ferroelectric properties of multiferroic Mn1-xCoxWO4 for x=0.15,0.135, and 0.17. For x=0.15, which is the critical doping that separates ground state AF5 and AF2/4 magnetic phases, the positive b-axis polarization(Pb) is reversed spontaneously at ~ 7K, when the magnetic field along c-axis is >= 20 kOe even for the positive poling voltage. From the polarization measurement for x=0.135 and 0.17, we found that Pb originates from both AF5 and AF2/4 phases, however, c-axis magnetic field of >= 20 kOe is needed for former case which is the effect of spin flop transition. Magnetic data for x=0.135 clearly show the existence of spin flop transition in a c-axis magnetic field. By comparing similar data for x=0.15 we conclude that the spin flop also happens in the AF5 phase which coexists with AF2/4 magnetic structure. The polarization reversal is explained by a coupling of different domains preserving the chirality of the spiral spin structure. Supported by DOE, the AFOSR, the T.L.L Temple Foundation, the J.J. and R. Moores Endowment, and the State of Texas(TCSUH).
Ordering of apolar and polar solutes in nematic solvents
NASA Astrophysics Data System (ADS)
Dingemans, T.; Photinos, D. J.; Samulski, E. T.; Terzis, A. F.; Wutz, C.
2003-04-01
The quadrupolar splittings of deuteriated para- and ortho-dichlorobenzene (1,4-DCB and 1,2-DCB, respectively) are measured by nuclear magnetic resonance (NMR) in the nematic solvents hexyl- and pentyloxy-substituted diphenyl diacetylene (DPDA-C6 and DPDA-OC5, respectively). Measurements are taken for all four combinations of the nominally apolar (1,4-DCB) and polar (1,2-DCB) solutes in the apolar (DPDA-C6) and polar (DPDA-OC5) solvents, and throughout the entire nematic temperature range of the solutions. The temperature dependence of the second-rank orientational order parameters of the solutes are obtained from these measurements and the respective order parameters of the mesogenic cores of solvent molecules are obtained independently from carbon-13 NMR measurements. The order parameter profiles of the two solutes are found to be very different but show little variation from one solvent to the other. The results are analyzed and interpreted in terms of the underlying molecular interactions using atomistic solvent-solute potentials. The influence of electrostatic interactions on solute ordering is directly evaluated by computing the order parameters with and without the electrostatic component of the atomistic potential. It is observed to be small. It is also found that the important interactions in these solvent-solute systems are operative over short intermolecular distances for which the representation of the partial charge distributions in terms of overall molecular dipole and quadrupole moments is not valid.
NASA Astrophysics Data System (ADS)
Khan, Mahmud; Gschneidner, K. A., Jr.; Pecharsky, V. K.
2009-12-01
Heat capacity measurements in zero and applied magnetic fields have been performed on a series of Er1-xTbxAl2 pseudobinary Laves-phase alloys. Different anomalies that change with Tb concentrations have been observed. These anomalies represent multiple magnetic ordering phenomena, similar to those reported in Er1-xPrx and Er1-xDyxAl2 alloys. In common, all alloys contain mixtures of lanthanide metals with opposite signs of the second-order Steven’s operators, which were believed to cause competition between the magnetoelastic, crystalline electric field, and quadrupolar effects. This competition gives rise to the observed multiple magnetic ordering transitions in Er1-xPrx and Er1-xDyxAl2 alloys. Tb and Er also have opposite signs of second-order Steven’s factors, and therefore the observed anomalies in the Er1-xTbxAl2 alloys may also be interpreted in terms of competing quadrupolar, magnetoelastic, and crystalline electric field effects. The magnetocaloric properties of the Er1-xTbxAl2 alloy system have also been evaluated.
O'Brien, Daniel B; Massari, Aaron M
2015-01-14
The generalized optical interference model for interfacial contributions to vibrational sum frequency generation (VSFG) spectroscopic signals from organic thin film systems is extended to include a description of optical interferences contained in the thin film bulk response. This is based on electric quadrupolar interactions with the input fields and includes a discussion on possible contribution from the electric quadrupolar polarization. VSFG data from the first of this two part report are analyzed and include effects from higher order responses, for both bulk and higher order interfacial terms. The results indicate that although it is capable of capturing many of the data features, the electric dipole treatment is likely not a complete description of the VSFG intensity data from this system. An analysis based on the signs of the resulting response amplitudes is used to deduce the relative magnitude of the electric dipole and higher order interfacial terms. It is found that the buried interface is closer to satisfying the electric dipole approximation, consistent with smaller field gradients due to closer index matching between the organic thin film and substrate relative to air. The procedure outlined in this work allows for the difficult task of deducing a physical picture of average molecular orientation at the buried interface of a multilayer organic thin film system while including higher order effects. PMID:25591374
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...
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.
NSDL National Science Digital Library
This activity helps students develop a sense of the relative size of quantities in the categories of temperature, speed, time duration and loudness. Learners rank their estimates of given measures in order from least to greatest and justify their decisions. Students are encouraged to do research and carry out experiments when possible. The Teachers' Notes page includes suggestions for implementation, discussion questions, ideas for extension and support, and links to related activities.
Hyperfine interactions in titanates: Study of orbital ordering and local magnetic properties
Agzamova, P. A., E-mail: polina_agzamova@usu.ru; Leskova, Yu. V.; Nikiforov, A. E. [Ural Federal University (Russian Federation)
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.
The 4f multipole ordering effect on core-level spectroscopies of Ce intermetallics
NASA Astrophysics Data System (ADS)
Sasabe, Norimasa; Tonai, Hironori; Uozumi, Takayuki
2015-03-01
The 3d transition metal compounds and 4f rare earth compounds show attractive phenomena, such as superconductivity and Kondo effect, due to strong electron correlations among localized 3d and 4f electrons. Especially, multipole ordering of orbital and/or spin in 4f and 5f compounds is 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 a simplified RKKY interaction.
Acoustic assisted actuation of Ni-Mn-Ga ferromagnetic shape memory alloys
Peterson, Bradley William
2006-01-01
Ferromagnetic shape memory alloys (FSMA) have been shown in recent work to exhibit large magnetic field induced strains. The material generally requires a large threshold field (of order 3-4 kOe) to initiate the strain. ...
Composite Spin and Quadrupole Wave in the Ordered Phase of Tb2+xTi2-xO7+y
NASA Astrophysics Data System (ADS)
Kadowaki, H.; Takatsu, H.; Taniguchi, T.; Fåk, B.; Ollivier, J.
2015-07-01
The hidden ordered state of the frustrated pyrochlore oxide Tb2+xTi2-xO7+y is possibly one of the two electric multipolar, or quadrupolar, states of the effective pseudospin-1/2 Hamiltonian derived from crystal-field ground state doublets of non-Kramers Tb3+ ions. These long-range orders are antiparallel or parallel alignments of transverse pseudospin components representing electric quadrupole moments, which cannot be observed as magnetic Bragg reflections by neutron scattering. However, pseudospin waves of these states are composite waves of the magnetic-dipole and electric-quadrupole moments, and can be partly observed by inelastic magnetic neutron scattering. We calculate these spin-quadrupole waves using linear spin-wave theory and discuss previously observed low-energy magnetic excitation spectra of a polycrystalline sample with x = 0.005(Tc = 0.5 K).
NASA Astrophysics Data System (ADS)
Li, Qingxiang; Gandhi, Om P.
2005-01-01
Compliance testing of electronic article surveillance (EAS) devices requires that induced current densities in central nervous system (CNS) tissues, i.e. brain and the spinal cord, be less than the prescribed safety limits. Even though ferromagnetic cores are mostly used for activation/deactivation of embedded magnetic tags, assumed equivalent air-core coils with guessed increased number of ampere turns have always been used to calculate the magnetic fields for the proximal region to which a customer is exposed. We show that at low frequencies up to several kilohertz, duality of electric and magnetic circuits may be exploited such that the shaped high reluctance core is modelled as though it was a higher conductivity electric circuit of the corresponding shape. The proposed procedure is tested by examples of two magnetic cores typical of countertop activation/deactivation devices. The equivalent exposure magnetic fields obtained from the dual electric fields are shown to be in excellent agreement (within ±5%) with those measured for these ferromagnetic EAS devices. The previously proposed impedance method is then used to calculate the induced current densities for a 1.974 × 1.974 × 2.93 mm resolution anatomic model of a human. For the two considered EAS systems using excitation currents of 5000 A turns at 200 Hz, the maximum 1 cm2 area-averaged induced current densities in the CNS tissues are calculated and found to be less than the ICNIRP safety limits.
Dordevic, S.V.; Gozar, A.; Kohlman, L.W.; Tung, L.C.; Wang, Y.-J.; Logvenov, G.; Bozovic, I.
2009-04-01
We report magnetotransmission measurements on a series of La{sub 2-x}Sr{sub x}CuO{sub 4} thin films. The measurements were performed in magnetic fields of 18 T, on films with doping levels of x = 0, 0.01, 0.03, 0.045, 0.06, 0.08, and 0.10. In addition, an optimally doped film (x = 0.16) was studied in magnetic fields up to 33 T, both above and below its superconducting critical temperature T{sub c} = 41 K. A combination of Gaussian and wavelet filtering was employed to improve the signal-to-noise ratio of the data. However, even after this procedure, we could not detect any field-induced changes of transmission in any of the studied samples. Our results therefore rule out a direct relation between intensity changes in mid-infrared charge excitations and a bosonic mode in the far infrared. We discuss these observations in the context of existing proposals regarding the nature of medium energy range excitations in the cuprates.
Sándor, Katalin; Helyes, Zsuzsanna; Gyires, Klára; Szolcsányi, János; László, János
2007-06-20
Data concerning the effect of static magnetic field (SMF) on nociceptive processes are contradictory in the literature probably due to differences in species, characteristics of the magnetic fields, and duration of the exposure. The aim of the present series of experiments was to elucidate the action of acute full-body exposure of mice to a special SMF developed and validated by us on acute visceral and somatic chemonociception and inflammatory mechanical hyperalgesia. SMF exposure significantly diminished the number of acetic acid- or MgSO4-induced abdominal contractions (acute visceral nociception), formalin-evoked paw lickings and liftings in both phase I (acute somatic nociception) and phase II (acute inflammatory nociception) and mechanical hyperalgesia evoked by i.pl. injection of carrageenan as well as the TRPV1 capsaicin receptor agonist resiniferatoxin. Selective inactivation of capsaicin-sensitive sensory fibres by high dose resiniferatoxin pretreatment decreased nocifensive behaviours in phase II of the formalin test to a similar extent suggesting that pro-inflammatory neuropeptides such as substance P and calcitonin gene-related peptide released from these fibres are involved in this inflammatory reaction. Significant inhibitory effects of SMF on formalin-induced nociception and carrageenan-evoked hyperalgesia were absent in resiniferatoxin-pretreated mice, which also points out that capsaicin-sensitive nerves are involved in the SMF-induced anti-nociceptive action. PMID:17568617
Christianson, Andrew D [ORNL; Goremychkin, E. A. [ISIS Facility, Rutherford Appleton Laboratory; Gardner, J. S. [Indiana University; Kang, H. J. [National Institute of Standards and Technology (NIST); Chung, J.-H. [National Institute of Standards and Technology (NIST); Manuel, P. [ISIS Facility, Rutherford Appleton Laboratory; Thompson, J. D. [Los Alamos National Laboratory (LANL); Sarrao, J. L. [Los Alamos National Laboratory (LANL); Lawrence, J. M. [University of California, Irvine
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.
Magnetic Field Induced Charged Exciton Studies in a GaAs/Al(0.3)Ga(0.7)As Single Heterojunction
Kim, Yongmin; Munteanu, F.M.; Perry, C.H.; Reno, J.L.; Rickel, D.G.; Simmons, J.A.
1999-05-25
The magnetophotoluminescence (MPL) behavior of a GaAs/Al_{0.3}Ga_{0.7}As single heterojunction has been investigated to 60T. We observed negatively charged singlet and triplet exciton states that are formed at high magnetic fields beyond the {nu}=l quantum Hall state. The variation of the charged exciton binding energies are in good agreement with theoretical predictions. The MPL transition intensities for these states showed intensity variations (maxima and minima) at the {nu}=l/3 and 1/5 fractional quantum Hall (FQH) state as a consequence of a large reduction of electron-hole screening at these filling factors.
Friedman, Jonathan R.
at higher fields in several materials. In two-dimensional modulation-doped GaAs/AlxGa1 xAs het. At much higher fields, the orbital shrinkage of the impurity wave functions is expected to give a rapid found in two dimensions, and which we attributed to the mechanism proposed by Raikh.5,12 In deeply
Solving the viscous hydrodynamics order by order
Gao, Jian-Hua
2014-01-01
In this paper, we propose a method of solving the viscous hydrodynamics order by order in a derivative expansion. In such method, the zero order solution is just the one of the ideal hydrodynamics. All the other higher order corrections satisfy the same first-order partial differential equations but with different inhomogeneous terms. We therefore argue that our method could be easily extended to any orders. The problem of causality and stability will be released if the gradient expansion is guaranteed. This method might be of great help to both theoretical and numerical calculations of relativistic hydrodynamics.
FRENCH ORDER WITHOUT ORDER* Gabriel G. B~
FRENCH ORDER WITHOUT ORDER* Gabriel G. B~ Universit6 Blaise Pascal - Clermont II, Formation Universit6 Blaise Pascal -Clermont II and University of Edinburgh, Centre for Cognitive Science, 2 Buccleuch
Quadrupolar contact terms and Hyperfine Structure
G. Karl; V. A. Novikov
2006-04-06
In the interaction of two electric quadrupoles, there is at short distances a contact term proportional to the second derivative of a delta function. This contact term contributes to the hyperfine splitting of bound states of two particles with spin one or higher-for example the bound states of Omega minus and a nucleus of spin one.The contact hyperfine splitting occurs in states with orbital angular momentum one(p-wave), in contrast to the Fermi contact interaction which is in s-states.We find that these contact splittings will be observable with Omega minus atoms and help measure the quadrupole moment and charge radius of the hyperon.
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 ?E, which we predict to scale with the number of atoms N as ?E˜1 /N3 /2 . This gives rise to anomalies in the specific heat and the susceptibility at temperatures T ˜?E and produces distinct structures in the magnetic excitation spectrum of the clusters that should be possible to detect experimentally.
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.
Order parameters of a transmembrane helix in a fluid bilayer: case study of a WALP peptide.
Holt, Andrea; Rougier, Léa; Réat, Valérie; Jolibois, Franck; Saurel, Olivier; Czaplicki, Jerzy; Killian, J Antoinette; Milon, Alain
2010-05-19
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 (13)C and (15)N chemical shift anisotropies and (13)C-(15)N dipolar couplings, were determined from two different triple-isotope-labeled WALP23 peptides ((2)H, (13)C, and (15)N) 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 degrees was determined for WALP23 in dimyristoylphosphatidylcholine, which is much larger than the tilt angle of 5.5 degrees previously determined from (2)H NMR experiments. This approach provided a realistic value for the tilt angle of WALP23 peptide in the presence of hydrophobic mismatch, and can be applied to any transmembrane helical peptide. The influence of the experimental data set on the solution space is discussed, as are potential sources of error. PMID:20441750
Verchenko, Valeriy Yu; Tsirlin, Alexander A; Sobolev, Alexei V; Presniakov, Igor A; Shevelkov, Andrei V
2015-09-01
The ternary transition-metal compound Fe3-?GeTe2 is formed for 0 < ? < 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 Fe2.9GeTe2 via neutron diffraction, thermodynamic and transport measurements, Mössbauer spectroscopy, and electronic structure calculations. Below TC = 225 K, Fe2.9GeTe2 is ferromagnetically ordered with the magnetic moments of 1.95(5) and 1.56(4) ?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, -?S ? 1.1 J·kg(-1)·K(-1) at 5 T, is found. PMID:26267350
Effect of La Substitution in PrIr2Zn20 on the Superconductivity and Antiferro-Quadrupole Order
NASA Astrophysics Data System (ADS)
Matsumoto, Keisuke T.; Onimaru, Takahiro; Wakiya, Kazuhei; Umeo, Kazunori; Takabatake, Toshiro
2015-06-01
The electrical resistivity ? and the specific heat C of Pr1?xLaxIr2Zn20 (0 ? x ? 1) were measured to study the effect of La substitution in PrIr2Zn20 on the superconducting transition at Tc = 0.05 K and the antiferro-quadrupolar (AFQ) order at TQ = 0.11 K, which occur in a nonmagnetic ?3 doublet ground state. For x = 0.04, a cusp in C(T) due to the AFQ order was observed at TQ = 0.07 K, while the cusp disappeared for x ? 0.09, indicating that the AFQ order rapidly collapses with the dilution of the Pr lattice. On the other hand, in the whole range of 0 ? x ? 1, the superconducting transition to zero resistance was observed. With increasing x, Tc hardly changes up to x = 0.47, above which Tc increases linearly with x. The results indicate a rather weak interplay between Tc and TQ. We have measured the magnetic field variation of Tc to determine the upper critical field of the superconducting state. The estimated effective mass m* for x = 0 is twice larger than that for x = 1, suggesting that moderately strong hybridization between 4f and conduction electrons stabilizes the superconducting state in PrIr2Zn20.
Hsieh, C H; Wu, W G
1995-01-01
The molecular order and hydration properties of the amine group in phosphatidylethanolamine and its N-methyl derivatives were studied by 2H-NMR at subzero temperatures. Three coexisting signals with 2H-NMR quadrupolar splittings of 146, 106, and 28.8 KHz were detected from the fully hydrated phosphatidylethanolamine/D2O at the lowest studied temperature of -120 degrees C by using short recycle time in the applied NMR pulse sequence. These signals have been assigned to originate from frozen D2O in the interbilayer space and the deuterated amine group, i.e., -ND, with and without threefold symmetric motions. Comparative 2H-NMR studies of phosphatidylethanolamine/D2O with different degrees of methylation over a temperature range between -40 and -120 degrees C lead to the following conclusions. First, the bond angle of -D attached to the nitrogen atom of the amine group may be determined by the 2H-NMR quadrupolar splittings, i.e., 106 and 28.8 KHz, of the two coexisting signals of the deuterated amine group and found to be 112.9 for the gel-state phosphatidylethanolamine. Second, assuming the applicability of the empirical equation for the hydrogen bond distance of N+D--O with deuteron quadrupole coupling constants and using the intermolecular hydrogen bond distance of the amine group determined in single crystals of phosphatidylethanolamine bilayers, the largest measured quadrupolar splitting (delta nu Q) of N-D in this study, i.e., 106 KHz, is close to the static value. This interpretation is also consistent with the fact that the delta nu Q value determined remains constant in the temperature range between -70 and -120 degrees C. Third, the molecular order parameter of the amine group, as calculated from the ratio of the libration-averaged and static delta nu Q value for the lipid with different degrees of methylation, suggests that the perturbation of the headgroup interaction is most significant for the final methylation step. Finally, measurement of the spectral intensity of isotropic unfrozen D2O signals in D2O/phospholipid dispersions at temperatures below the homogeneous nucleation temperature of ice formation for D2O, i.e., below -34 degrees C, suggests that the first methylation step perturbs the neighboring water most significantly. Assuming that the molecular order of the amine group and the amount of unfrozen water detected under the present experimental condition can be taken as a measure of the hydrogen-bonding ability and the extent of perturbation caused by the methyl group, respectively, the gradual methylation of the amine group perturbs the interactions of the N-methylated headgroups in a nonlinear fashion. The results provide a molecular explanation for the phase behavior of phospholipids with different degrees of methylation. PMID:8599659
Extending Partial Orders to Dense Linear Orders
Theodore A. Slaman; W. Hugh Woodin
1998-01-01
J. ?o? raised the following question: Under what conditions can a countable partially ordered set be extended to a dense linear order merely by adding instances of comparability (without adding new points)? We show that having such an extension is a ?1l-complete property and so there is no Borel answer to ?o?'s question. Additionally, we show that there is a
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.
Blueberries Cost/ # Ordered Total
Liskiewicz, Maciej
Blueberries Cost/ Plant # Ordered Total Early Season · Spartan............... $6.00 x.00 x _______ $ ________.00 TOTAL BLUEBERRIES AMOUNT: $ ________.00 Strawberries # Ordered Total x will benefit the Grayson County 4-H Program. Blueberries Strawberries #12;Blueberry Plant Varieties Spartan
NSDL National Science Digital Library
This activity allows the user to practice order of operations with addition/subtraction, multiplication/division, exponents, and parentheses. Order of Operations Quiz is one of the Interactivate assessment quizzes.
NSDL National Science Digital Library
Kyle Siegrist
This resource consists of a Java applet and expository text. The applet simulates the order statistics of a random sample from a given distribution. The sample size, order, and sampling distribution can be specified.
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.
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.
NSDL National Science Digital Library
Mrs. Nieman
2008-10-05
Students will learn order of operations. PEMDAS will become a helpful acronym for successfully mastering order of operations. Students will learn the importance of solving problems using order of operations. An acronym will be introduced that will help them remember the order of operations. Interactive guidance and practice will be available for students to access. This tutorial will include the following learning modules: 1) motivation and ...
Publications Order Form Order by Mail
Brown, Sally
-2100 *Note: Orders may take 7 - 10 days for arrival. Title Forest Pruning and Wood Quality of Western North and Pacific Northwest Skyline Symposium, 1992 Douglas-Fir: Stand Management for the Future The Burning.00 $10.50 $5.00 $10.00 $35.00 $20.00 Quantity Total books Total $ $ $ $ $ $ $ $ $ $ $ $ $ $ Total Cost
Superconductors are topologically ordered
Hans Hansson; Vadim Oganesyan; Shivaji Sondhi
2003-01-01
We revisit a venerable question: what is the nature of the ordering in a superconductor? We find that the answer is properly that the superconducting state exhibits topological order in the sense of Wen, i.e. that while it lacks a local order parameter, it is sensitive to the (global) topology of the underlying manifold. We show that this perspective unifies
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.
Pallab Basu; Jianyang He; Anindya Mukherjee; Moshe Rozali; Hsien-Hang Shieh
2010-10-06
We model competition between different macroscopic orders in an holographic context. The orders we considered are a superconducting order, modeled by a charged scalar field, and a magnetic order modeled by a neutral scalar field. We also discuss the case of two competing scalars coupled to a single gauge field. In all cases discussed here the phases tend to compete, rather than enhance each other. The condensation of one scalar hinders any further instabilities, unless we have a sufficiently strong repulsive interactions between the bulk scalars. We provide both analytic arguments and numerical demonstration of this fact. Based on the cases discussed here, we conjecture that holographic orders tend to compete for attractive bulk interactions, including gravity, and to cooperate, or be mutually enhancing, for repulsive bulk interactions between the corresponding order parameters.
Katz, M.G.
1995-02-01
Through its Order 636, the Federal Energy Regulatory Commission (FERC) completed a restructuring of the natural gas industry. The order severed the last links in the chain linking gas producers to pipeline companies to local gas distribution companies (LDCs) to customers. Before Order 636 took effect, many predicted electric power generation, particularly by cogenerators and independent power producers (IPPs), would be a major growth area for natural gas. In fact, what Order 636 has shown is, that timing is everything, and that it`s difficult to sort out the effect of one agent of change when many others are at work.
First order differential equations
Samy Tindel
2015-09-14
dt. = 1. 2 e. 5t. 6. ?? y(t) = 3. 5 e t. 3 + c e? t. 2. Samy T. First order equations. Differential equations. 8 / 100 ... e? t. 2. Direction fields and integral curves: Samy T. First order equations. Differential equations ...... Logistic growth. Hypothesis:.
Finite Order Statistic Experiment
NSDL National Science Digital Library
Kyle Siegrist
This resource consists of a Java applet and expository text. The applet is a simulation of the experiment of selecting n objects at random from the first m positive integers. The random variables of interest are the order statistics. The applet illustrates the distributions of the order statistics.
NSDL National Science Digital Library
2011-01-01
In this 7-minute video, users learn how to compare and order fractions. The video shows visual representations and guides the learner through steps for comparing and ordering like-denominator fractions, unit fractions, and fractions with unlike denominators (by using equivalent fractions).
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…
Bruggeman, Roelof
2010-01-01
We determine the size of spaces of higher order Maass forms of even weight for cofinite discrete subgroups of PSL(2,R) with cusps. If exponential growth at the cusps is allowed, the spaces of Maass forms of a given order are as large as algebraic constrictions allow. We show the analogous statement for the spaces of holomorphic forms. For functions on the universal covering group of PSL(2,R) we introduce the concept of generalized weight. For the resulting spaces of higher order Maass forms with even generalized weight we show that the size is maximal.
MedlinePLUS Videos and Cool Tools
... to find out if birth order affected adult women’s height and weight. They looked at health records ... you. Related MedlinePlus Health Topics Family History Obesity Women's Health About MedlinePlus Site Map FAQs Contact Us ...
Atmospheric Science Data Center
2012-04-17
... and spatial coordinates; additional latitude and longitude layers, and unpacking and unscaling applicable fields; and output data in ... Reverb Tutorial Client for searching and ordering Earth science data from various NASA and affiliated centers. Reverb, developed ...
Li, Zhipeng (Zhipeng Simon)
2007-01-01
Online purchasing is now popular following the growth of E-business. Retailers ordering online will get the exact delivery date of goods for their better management of sales operations. Suppliers should keep their competence ...
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.
NASA Astrophysics Data System (ADS)
Espin, Johnny; Krasnov, Kirill
2015-06-01
It is known, though not commonly, that one can describe fermions using a second order in derivatives Lagrangian instead of the first order Dirac one. In this description the propagator is scalar, and the complexity is shifted to the vertex, which contains a derivative operator. In this paper we rewrite the Lagrangian of the fermionic sector of the Standard Model in such second order form. The new Lagrangian is extremely compact, and is obtained from the usual first order Lagrangian by integrating out all primed (or dotted) 2-component spinors. It thus contains just half of the 2-component spinors that appear in the usual Lagrangian, which suggests a new perspective on unification. We sketch a natural in this framework SU (2) × SU (4) ? SO (9) unified theory.
NSDL National Science Digital Library
Amanda Hayler and Dan Bunker
2004-01-01
This interactive Flash applet helps students learn to compare and order objects according to size and weight attributes. The text and voice prompts ask students to compare three objects to find the longest, tallest, shortest, and so on. It then asks them to place three objects in a specified order, such as narrowest to widest. Correct responses are rewarded with a cheer and a summary of the results. One concern for users might be the British accents of the readers.
NSDL National Science Digital Library
2008-01-01
This interactive Java applet allows users to plot ordered pairs on the Cartesian coordinate plane. The applet plots the points in the order they are entered. By selecting the option Plot Type: Connected, the user can create shapes. Other options include entering multiple data sets for comparison, changing the dimensions of the x- and y-axes, zoom and pan features, and grid line display.
Birth Order and Psychopathology
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
Templated quasicrystalline molecular ordering.
Smerdon, J A; Young, K M; Lowe, M; Hars, S S; Yadav, T P; Hesp, D; Dhanak, V R; Tsai, A P; Sharma, H R; McGrath, R
2014-03-12
Quasicrystals are materials with long-range ordering but no periodicity. We report scanning tunneling microscopy (STM) observations of quasicrystalline molecular layers on 5-fold quasicrystal surfaces. The molecules adopt positions and orientations on the surface consistent with the quasicrystalline ordering of the substrate. Carbon-60 adsorbs atop sufficiently separated Fe atoms on icosahedral Al-Cu-Fe to form a unique quasicrystalline lattice, whereas further C60 molecules decorate remaining surface Fe atoms in a quasi-degenerate fashion. Pentacene (Pn) adsorbs at 10-fold symmetric points around surface-bisected rhombic triacontahedral clusters in icosahedral Ag-In-Yb. These systems constitute the first demonstrations of quasicrystalline molecular ordering on a template. PMID:24528205
NASA Astrophysics Data System (ADS)
van Wezel, Jasper; Flicker, Felix
2015-03-01
Incommensurate charge density waves occur in a large variety of materials in one, two and even three dimensions. As a function of decreasing temperature or applied pressure, the propagation vector characterizing such charge order typically evolves smoothly towards a commensurate value, before discontinuously jumping to a fully commensurate phase. This so-called lock-in transition is often explained in terms of a proliferation of discommensurations, which separate local regions of commensurate CDW within a globally incommensurate structure. Here, we argue that in strongly incommensurate systems with a sharply peaked electronic susceptibility, a second possibility exists. Rather than forming a regular array of discommensurations, we show that within an extended region of parameter space, the system may lower its free energy further by forming a quasicrystalline charge ordered state. The characteristic properties of this novel implementation of a quasicrystal, as well as its effect on the phase diagram and wave vector evolution of typical incommensurate charge ordered materials will be discussed.
NSDL National Science Digital Library
The US Department of Education recently launched this site to offer one-stop, public access to free copies of publications, posters, videos, CD-ROMS, and a comprehensive array of other Department of Education products. Users can browse by topic or conduct either a keyword or advanced search to locate items of interest, which can be ordered at the site. There is currently a one item per order limit. A number of resources are available in Spanish, as well as alternate formats such as Braille, large print, disks, and captioned videotapes.
WLN Online Order Transmission.
ERIC Educational Resources Information Center
Ziegman, Bruce; Aveney, Brian
1982-01-01
Describes features of the acquisitions subsystem of the online computer system introduced by the Washington Library Network and offered to all participants who use the subsystem and all interested vendors, noting equipment and programs used, and online ordering procedures available. (EJS)
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…
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…
Johnny Espin
2015-09-19
It has been proposed several times in the past that one can obtain an equivalent, but in many aspects simpler description of fermions by first reformulating their first-order (Dirac) Lagrangian in terms of two-component spinors, and then integrating out the spinors of one chirality ($e.g.$ primed or dotted). The resulting new Lagrangian is second-order in derivatives, and contains two-component spinors of only one chirality. The new second-order formulation simplifies the fermion Feynman rules of the theory considerably, $e.g.$ the propagator becomes a multiple of an identity matrix in the field space. The aim of this thesis is to work out the details of this formulation for theories such as Quantum Electrodynamics, and the Standard Model of elementary particles. After having developed the tools necessary to establish the second-order formalism as an equivalent approach to spinor field theories, we proceed with some important consistency checks that the new formulation is required to pass, namely the presence or absence of anomalies in their perturbative and non-perturbative description, and the unitarity of the S-Matrix derived from their Lagrangian. Another aspect which is studied is unification, where we seek novel gauge-groups that can be used to embed all of the Standard Model content: forces and fermionic representations. Finally, we will explore the possibility to unify gravity and the Standard Model when the former is seen as a diffeomorphism invariant gauge-theory.
Loredana Afanasiev; Patrick Blackburn; Ioanna Dimitriou; B. Gaiffe; Evan Goris; Maarten Marx; Maarten de Rijke
2004-01-01
This paper is about a special version of PDL, designed by Mar- cus Kracht for reasoning about sibling ordered trees. It has four basic programs corresponding to the child, parent, left- and right-sibling re- lations in such trees. The original motivation for this language is rooted in the field of model-theoretic syntax. Motivated by recent develop- ments in the area
Hoffmann, J; Sebastia, L; 10.1613/jair.1492
2011-01-01
Many known planning tasks have inherent constraints concerning the best order in which to achieve the goals. A number of research efforts have been made to detect such constraints and to use them for guiding search, in the hope of speeding up the planning process. We go beyond the previous approaches by considering ordering constraints not only over the (top-level) goals, but also over the sub-goals that will necessarily arise during planning. Landmarks are facts that must be true at some point in every valid solution plan. We extend Koehler and Hoffmann's definition of reasonable orders between top level goals to the more general case of landmarks. We show how landmarks can be found, how their reasonable orders can be approximated, and how this information can be used to decompose a given planning task into several smaller sub-tasks. Our methodology is completely domain- and planner-independent. The implementation demonstrates that the approach can yield significant runtime performance improvements when used...
NASA Astrophysics Data System (ADS)
Ma, Evan
2015-06-01
Recent research has revealed considerable diversity in the short-range ordering of metallic glass, identifying favoured and unfavoured local atomic configurations coexisting in an inhomogeneous amorphous structure. Tailoring the population of these local motifs may selectively enhance a desired property.
NSDL National Science Digital Library
2012-01-01
This interactive game reinforces the importance of the order of operations within equations. Players enter the three numbers on the rocks in the correct box to make a true closed equation. A check answer button provides feedback and there are three levels of difficulty to provide challenge at the student's skill level.
Espin, Johnny
2015-01-01
It has been proposed several times in the past that one can obtain an equivalent, but in many aspects simpler description of fermions by first reformulating their first-order (Dirac) Lagrangian in terms of two-component spinors, and then integrating out the spinors of one chirality ($e.g.$ primed or dotted). The resulting new Lagrangian is second-order in derivatives, and contains two-component spinors of only one chirality. The new second-order formulation simplifies the fermion Feynman rules of the theory considerably, $e.g.$ the propagator becomes a multiple of an identity matrix in the field space. The aim of this thesis is to work out the details of this formulation for theories such as Quantum Electrodynamics, and the Standard Model of elementary particles. After having developed the tools necessary to establish the second-order formalism as an equivalent approach to spinor field theories, we proceed with some important consistency checks that the new formulation is required to pass, namely the presence...
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)
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...
Representations of quantum orders
Panov, A N
2010-01-01
We study finite dimensional algebras that appear as fibers of quantum orders over a given point of variety of center. We present the formula for the number of irreducible representations and check it for it for the algebra of twisted polynomials, the quantum Weyl algebra and the algebra of regular functions on quantum group.
These conditions must be imposed on the solution (1.1.4) in order to ... We now build a mathematical model describing the cooling (or heating) of an object. ... We assume that every curve in the family F (x, y, c) = 0 has a well-de?ned tangent
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.
NASA Astrophysics Data System (ADS)
Calucci, Lucia; Geppi, Marco; Marini, Alberto; Veracini, Carlo Alberto
2010-10-01
Structural and orientational order properties of the liquid crystal 4,4' -bis-heptyl-azoxybenzene (HAB) have been obtained in its nematic and smectic- A phases by simultaneously analyzing several observables extracted from H2 and C13 nuclear magnetic resonance (NMR) spectra, i.e., H2 quadrupolar, H2-H1 and C13-H2 dipolar couplings, as well as C13 chemical shift anisotropy. C13 experiments required the application of high-resolution solid-state NMR techniques like H1 high-power decoupling and cross polarization, as well as the independent determination of chemical shift tensors by means of density functional theory (DFT) calculations, here performed taking into account the effect of the anisotropic medium by the polarizable continuum model method. The approach, consisting in the simultaneous analysis of all the H2 and C13 experimental data to derive orientational order parameters, and in the use of geometrical parameters determined by DFT methods, allows more detailed and reliable results to be obtained with respect to the traditional approach based on the sole analysis of H2 experiments.
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 ? -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.
Mrs. Asuman's emergency order.
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
Prochaska, Elizabeth; Lomri, Sara
2014-11-01
Court-ordered caesarean sections are in the news after a number of recent legal decisions authorising surgery for women who lack mental capacity to consent. The decisions have not always been based on good evidence and they raise serious concerns about the protection of the rights of mentally ill women. The authors explain the legal process and question the wisdom of recent judgements. PMID:25582002
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.
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.
NASA Astrophysics Data System (ADS)
Deveaux, Vincent; Fernández, Roberto
2010-11-01
We provide a formal definition and study the basic properties of partially ordered random fields (PORF). These systems were proposed to model textures in image processing and to represent independence relations between random variables in statistics (in the latter case they are known as Bayesian networks). Our random fields are a generalization of probabilistic cellular automata (PCA) and their theory has features intermediate between that of discrete-time processes and the theory of statistical mechanical lattice fields. Its proper definition is based on the notion of partially ordered specification (POS), in close analogy to the theory of Gibbs measures. This paper contains two types of results. First, we present the basic elements of the general theory of PORFs: basic geometrical issues, definition in terms of conditional probability kernels, extremal decomposition, extremality and triviality, reconstruction starting from single-site kernels, relations between POM and Gibbs fields. Second, we prove three uniqueness criteria that correspond to the criteria known as uniform boundedness, Dobrushin uniqueness and disagreement percolation in the theory of Gibbs measures.
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 ? = 1.54 ?m. 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.)
Eberle, Richard; Ehlers, Bernhard; Hayward, Gary S.; McGeoch, Duncan J.; Minson, Anthony C.; Pellett, Philip E.; Roizman, Bernard; Studdert, Michael J.; Thiry, Etienne
2011-01-01
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
The high order chiral Lagrangian
NASA Astrophysics Data System (ADS)
Jiang, Shao-Zhou; Wang, Qing
2015-10-01
We obtain the full U group chiral Lagrangian to the order p6 order, and check the existing results. We find one more linear relation in p4 order at U group, and some more linear relations in p6 order at SU group with tensor sources.
Isotropic sequence order learning.
Porr, Bernd; Wörgötter, Florentin
2003-04-01
In this article, we present an isotropic unsupervised algorithm for temporal sequence learning. No special reward signal is used such that all inputs are completely isotropic. All input signals are bandpass filtered before converging onto a linear output neuron. All synaptic weights change according to the correlation of bandpass-filtered inputs with the derivative of the output. We investigate the algorithm in an open- and a closed-loop condition, the latter being defined by embedding the learning system into a behavioral feedback loop. In the open-loop condition, we find that the linear structure of the algorithm allows analytically calculating the shape of the weight change, which is strictly heterosynaptic and follows the shape of the weight change curves found in spike-time-dependent plasticity. Furthermore, we show that synaptic weights stabilize automatically when no more temporal differences exist between the inputs without additional normalizing measures. In the second part of this study, the algorithm is is placed in an environment that leads to closed sensor-motor loop. To this end, a robot is programmed with a prewired retraction reflex reaction in response to collisions. Through isotropic sequence order (ISO) learning, the robot achieves collision avoidance by learning the correlation between his early range-finder signals and the later occurring collision signal. Synaptic weights stabilize at the end of learning as theoretically predicted. Finally, we discuss the relation of ISO learning with other drive reinforcement models and with the commonly used temporal difference learning algorithm. This study is followed up by a mathematical analysis of the closed-loop situation in the companion article in this issue, "ISO Learning Approximates a Solution to the Inverse-Controller Problem in an Unsupervised Behavioral Paradigm" (pp. 865-884). PMID:12689389
Order sets utilization in a clinical order entry system.
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
Protective orders: questions and conundrums.
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
Yin, L. H.; Yang, J.; Zhao, B. C.; Liu, Y.; Tan, S. G.; Tang, X. W.; Dai, J. M.; Song, W. H. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Hefei 230031, People's Republic of China (China)] [Key Laboratory of Materials Physics, Institute of Solid State Physics, Hefei 230031, People's Republic of China (China); Sun, Y. P. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Hefei 230031, People's Republic of China (China) [Key Laboratory of Materials Physics, Institute of Solid State Physics, Hefei 230031, People's Republic of China (China); High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China (China)
2013-06-07
We prepared a series of Bi{sub 1-x}La{sub x}FeO{sub 3} (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 H{sub c}, which is attributed to the destruction of the cycloidal antiferromagnetic spin structure. The critical field H{sub c} decreases substantially from {approx}20 T for the x = 0 sample [Y. F. Popov et al., JETP Lett. 57, 69 (1993)] to {approx}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 H{sub c} increases with decreasing temperature. The variation of H{sub c} 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 (2P{sub r}) as high as {approx}64 {mu}C/cm{sup 2} is obtained for the x = 0.15 sample. These results may be important for potential applications in BiFeO{sub 3}-based magnetoelectric devices.
NCI Mouse Repository - Ordering Information
We have had a number of problems with orders and material transfer agreements (MTAs), so we have prepared instructions to shorten the time for processing orders. The MTA is a legal document. Therefore, please read these instructions completely before placing your order.
Semjon Adlaj
2011-10-03
A formula expressing a point of order 8 on an elliptic curve, in terms of the roots of the associated cubic polynomial, is given. Doubling such a point yields a point of order 4 distinct from the well-known points of order 4 given in standard references such as "A course of Modern Analysis" by Whittaker and Watson.
Commensurate-Incommensurate Magnetic Phase Transition in Magnetoelectric Single Crystal LiNiPO4
Zarestky, Jerel
Commensurate-Incommensurate Magnetic Phase Transition in Magnetoelectric Single Crystal LiNiPO4 D a spontaneous first-order commensurate- incommensurate magnetic phase transition. Short- and long in the spontaneous and magnetic- field induced commensurate-incommensurate magnetic (C-IC) transition over the years
Magneto-Thermo-Mechanical Response and Magneto-Caloric Effect in Magnetic Shape Memory Alloys
Yegin, Cengiz
2012-07-16
Ni-Co-Mn-In system is a new type of magnetic shape memory alloys (MSMAs) where the first order structural and magnetic phase transitions overlap. These materials can generate large reversible shape changes due to magnetic-field-induced martensitic...
Ordered Delinquency: The “Effects” of Birth Order On Delinquency
Cundiff, Patrick R.
2014-01-01
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 both 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
Energetic particles in the paleomagnetosphere: Reduced dipole configurations and quadrupolar
Kallenrode, May-Britt
with the supermagnetosonic and magnetized solar wind plasma to create the Earth's magnetosphere. Large-scale current systems 2007. [1] The Earth's magnetosphere acts as a shield against highly energetic particles of cosmic of a strongly reduced dipole moment, solar protons of several tens of MeV may access the Earth's atmosphere even
Surface melting of electronic order.
Wilkins, S. B.; Liu, X.; Wakabayashi, Y.; Kim, J.-W.; Ryan, P. J.; Mitchell, J. F.; Hill, J. P. (Materials Science Division); ( XSD); (BNL); (Osaka Univ.)
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.
Ordering relations for quantum states
NASA Astrophysics Data System (ADS)
Durham, Ian
2015-03-01
It is often desirable to model physical states in an order-theoretic manner, e.g. as a partially ordered set. Classical states are known to possess a unique ordering relation corresponding to a neo-realist interpretation of these states. No such unique relation exists for quantum states. This lack of a unique ordering relation for quantum states turns out to be a manifestation of quantum contextuality vis-à-vis the Kochen-Specker theorem. It also turns out that this provides a link to certain large-scale thermodynamic processes. The suggestion that the ordering of quantum states leads to macroscopic thermodynamic processes is at least five decades old. The suggestion that the mechanism that drives the ordering is contextuality, is unique to this work. The argument is framed in the language of the theories of domains, categories, and topoi. Financial support provided by FQXi.
NASA Astrophysics Data System (ADS)
Finkelstein, David
1992-09-01
Until now quantum logics has been first-order, but physics requires higher-order logics. We construct a natural higher-order language Q for quantum physics. Q is a finitistic logic based on Peano set theory and Grassmann algebra. Higher-order predicates are identified with their extensions, higher-rank sets. QAND and QOR (the AND and OR of Q) are naturally noncommutative but reduce to the commutative lattice operations for the first-order part of the language. We form higher-order predicates and sets by a setting operator similar to Peano's t that forms a simple extensor t ? = } ?} from any extensor ?. In a note added in proof, we correct Q so that a bond like {{?, ?}} between two fermions ? and ? is a quasiboson, as the application to lattice chromodynamics strongly suggests.
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…
Higher order anisotropies in hydrodynamics
M. Csanad; A. Szabo; S. Lokos; A. Bagoly
2015-04-29
In the last years it has been revealed that if measuring relative to higher order event planes $\\Psi_n$, higher order flow coefficients $v_n$ for $n>2$ can be measured. It also turned out that Bose-Einstein (HBT) correlation radii also show 3rd order oscillations if measured versus the third order event plane $\\Psi_3$. In this paper we investigate how these observables can be described via analytic hydro solutions and hydro parameterizations. We also investigate the time evolution of asymmetry coefficients and the mixing of velocity field asymmetries and density asymmetries.
Higher order anisotropies in hydrodynamics
Csanad, M; Lokos, S; Bagoly, A
2015-01-01
In the last years it has been revealed that if measuring relative to higher order event planes $\\Psi_n$, higher order flow coefficients $v_n$ for $n>2$ can be measured. It also turned out that Bose-Einstein (HBT) correlation radii also show 3rd order oscillations if measured versus the third order event plane $\\Psi_3$. In this paper we investigate how these observables can be described via analytic hydro solutions and hydro parameterizations. We also investigate the time evolution of asymmetry coefficients and the mixing of velocity field asymmetries and density asymmetries.
Code of Federal Regulations, 2012 CFR
2012-01-01
...MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....
Code of Federal Regulations, 2014 CFR
2014-01-01
...MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....
Code of Federal Regulations, 2011 CFR
2011-01-01
...MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....
Code of Federal Regulations, 2013 CFR
2013-01-01
...MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....
Code of Federal Regulations, 2010 CFR
2010-01-01
...MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....
Code of Federal Regulations, 2011 CFR
2011-01-01
...SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order...
Code of Federal Regulations, 2010 CFR
2010-01-01
...SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order...
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…
Introduction to Order of Operations
NSDL National Science Digital Library
2012-08-07
This video demonstration introduces order of operations for pre-algebra level learners. The presenter explains the correct order of operations (parentheses, exponents, multiplication/division, addition/subtraction) using a simple math problem as an introductory example. Flash is required to view the video. Running time for the video is 9:39.
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…
Tensions between Liberty and Order.
ERIC Educational Resources Information Center
Chemerinsky, Erwin
2002-01-01
Explores the issue of balancing liberty and order within the United States. Discusses the role of the Bill of Rights, focusing on the amendments in the document and the later amendments that ensure the liberty of U.S. citizens. Explains how order and liberty are ensured and includes discussion questions. (CMK)
Quantifying Order in Semiconducting Polymers
NASA Astrophysics Data System (ADS)
Snyder, Chad
2015-03-01
Semiconducting polymers form the basis for the burgeoning flexible electronics industry. However, quantifying their order can be challenging due to the nanophase separation induced by the side chains which are used to impart solubility, their propensity to form mesophases, and their often high levels of paracrystalline disorder. Recent successes in our laboratory in understanding these materials and quantifying their order will be presented.
High-order / low-order methods for ocean modeling
Newman, Christopher; Womeldorff, Geoff; Chacón, Luis; Knoll, Dana A.
2015-01-01
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 show how HOLO approaches, in particular the implicit-explicit method, can provide a solid route for ocean simulation to heterogeneous computing and exascale environments.
Constructing higher-order hydrodynamics: The third order
Grozdanov, Sašo
2015-01-01
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 systematisation of obtaining the hydrodynamic expansion to an arbitrarily high order. As an example, 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 the process, we list $20$ new transport coefficients in the conformal and $68$ in the non-conformal case. We also obtain the third-order corrections to the linear dispersion relations that describe the propagation of diffusion and sound waves in relativistic fluids. We apply our results to the energy-momentum transpo...
Constructing higher-order hydrodynamics: The third order
Sašo Grozdanov; Nikolaos Kaplis
2015-07-19
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 systematisation 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 the process, we list $20$ new transport coefficients in the conformal and $68$ in the non-conformal case, without considering any constraints that could potentially arise from the entropy current analysis. We also obtain the third-order corrections to the linear dispersion relations that describe the propagation of diffusion and sound waves in relativistic fluids. We apply our results to the energy-momentum transport in the $\\mathcal{N}=4$ supersymmetric Yang-Mills fluid at infinite 't Hooft coupling and infinite number of colours, to find the values of two new conformal transport coefficients.
Ordering chaos by random shortcuts.
Qi, Feng; Hou, Zhonghuai; Xin, Houwen
2003-08-01
In this Letter, the effects of random shortcuts in an array of coupled nonlinear chaotic pendulums and their ability to control the dynamical behavior of the system are investigated. We show that random shortcuts can induce periodic synchronized spatiotemporal motions, even though all oscillators are chaotic when uncoupled. This process exhibits a nonmonotonic dependence on the density of shortcuts. Specifically, there is an optimal amount of random shortcuts, which can induce the most ordered motion characterized by the largest order parameter that is introduced to measure the spatiotemporal order. Our results imply that topological randomness can tame spatiotemporal chaos. PMID:12935078
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.
Rajeev Singh; Subinay Dasgupta; Sitabhra Sinha
2010-11-23
Homogeneous populations of oscillators have recently been shown to exhibit stable coexistence of coherent and incoherent regions. Generalizing the concept of chimera states to the context of order-disorder transition in systems at thermal equilibrium, we show analytically that such complex ordering can appear in a system of Ising spins, possibly the simplest physical system exhibiting this phenomenon. We also show numerically the existence of chimera ordering in 3-dimensional spin systems that model layered magnetic materials, suggesting possible means of experimentally observing such states.
Complex higher order derivative theories
Margalli, Carlos A.; Vergara, J. David [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, Mexico 04510 DF (Mexico)
2012-08-24
In this work is considered a complex scalar field theory with higher order derivative terms and interactions. A procedure is developed to quantize consistently this system avoiding the presence of negative norm states. In order to achieve this goal the original real scalar high order field theory is extended to a complex space attaching a complex total derivative to the theory. Next, by imposing reality conditions the complex theory is mapped to a pair of interacting real scalar field theories without the presence of higher derivative terms.
Fluctuating Membranes with Tilt Order
Thomas Powers; Philip Nelson
1995-04-19
Thermal fluctuations are important for amphiphilic bilayer membranes since typical bending stiffnesses can be a few $k_B T$. The rod-like constituent molecules are generically tilted with respect to the local normal for packing reasons. We study the effects of fluctuations on membranes with nematic order, a simplified idealization with the same novel features as realistic tilt order. We find that nematic membranes lie in the same universality class as hexatic membranes, {\\it i.e.} the couplings that distinguish nematic from hexatic order are marginally irrelevant. Our calculation also illustrates the advantages of conformal gauge, which brings great conceptual and technical simplifications compared to the more popular Monge gauge.
Author Order and Research Quality
Kissan, Joseph; Laband, David N.; Patil, Vivek
2005-01-01
We observe a great deal of heterogeneity in the manner in which author orderings are assigned both across and within academic markets. To better understand this phenomenon, we develop and analyze a stochastic model of ...
Telecommunications WiMAX Order
Telecommunications WiMAX Order 1. Fax completed form to 979.847.1111. 2. If you do not receive Approval Signature Date Service Date Desired Telecommunications Office Use Only Service Due Date Print #12;
Exploring Krypto (Order of Operations)
NSDL National Science Digital Library
Illuminations National Council of Teachers of Mathematics
2009-07-21
"The rules of Krypto — combine five numbers using the standard arithmetic operations to create a target number. The game helps to develop number sense, computational skills, and an understanding of the order of operations" from NCTM's Illuminations.
Universal Cycles for Weak Orders
Horan, Victoria
2012-01-01
Universal cycles are generalizations of de Bruijn cycles and Gray codes that were introduced originally by Chung, Diaconis, and Graham in 1990. They have been developed by many authors since, for various combinatorial objects such as strings, subsets, permutations, partitions, vector spaces, and designs. One generalization of universal cycles, which require almost complete overlap of consecutive words, is s-overlap cycles, which relax such a constraint. In this paper we study weak orders, which are relations that are transitive and complete. We prove the existence of universal and s-overlap cycles for weak orders, as well as for fixed height and/or weight weak orders, and apply the results to cycles for ordered partitions as well.
VMI vs. order based fulfillment
Shen, Victoria W
2005-01-01
In this thesis, two inventory fulfillment methods are compared by evaluating the vendor managed inventory (VMI) fulfillment against the current order based fulfillment. Several forms of adaptation to VMI are described. The ...
Theses & Dissertations Binding Order Information
Gustafsson, Torgny
Theses & Dissertations Binding Order Information About this service... Many graduate students at Rutgers use the RUetd system to submit their theses and dissertations to their respective programs bindings can accommodate larger theses and dissertations. Contact and correspondence information Questions
Supersymmetric fifth order evolution equations
Tian, K.; Liu, Q. P.
2010-03-08
This paper considers supersymmetric fifth order evolution equations. Within the framework of symmetry approach, we give a list containing six equations, which are (potentially) integrable systems. Among these equations, the most interesting ones include a supersymmetric Sawada-Kotera equation and a novel supersymmetric fifth order KdV equation. For the latter, we supply some properties such as a Hamiltonian structures and a possible recursion operator.
J. Ross Quinlan
1996-01-01
. Several empirical studies have confirmed that boosting classifier-learning systems can lead to substantial improvements in predictiveaccuracy. This paper reports early experimental results from applyingboosting to ffoil, a first-order system that constructs definitions of functionalrelations. Although the evidence is less convincing than that forpropositional-level learning systems, it suggests that boosting will alsoprove beneficial for first-order induction.1 IntroductionDesigners...
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 ?B /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 ?B /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.
Order in a multidimensional system
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
Weighted Order Statistic Classifiers with Large Rank-Order Margin
Reid B. Porter; Damian Eads; Don R. Hush; James Theiler
2003-01-01
We investigate how stack filter function classes like weighted order statistics can be applied to 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 mea- sure of margin that is directly optimized as a standard linear program and investigate its relationship to regularization. Our approach
FIRST-ORDER SYSTEM LEAST SQUARES FOR SECOND-ORDER ...
1997-03-07
second-order uniformly elliptic partial differential equations in n = 2 or 3 ... elliptic in the H(div) × H1 norm and to yield optimal convergence for finite ... [11], is the solution of elliptic equations (including convection–diffusion and Helmholtz ...... a constant; their difference would yield a nonzero function of the form (2.37) that.
First Order Data Types and First Order Logic
Treinen, Ralf - Laboratoire Preuves, Programmes et Systèmes, Université Paris 7
*81]), the packages of Ada 1 ([DoD81], [ANSI83]), the modules of MODULA2([Wir85]) and the structures if and only if for the given data type definition the new logic has the same expressive power than first order Modules 5 3.1 Syntax : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 3
Code of Federal Regulations, 2011 CFR
2011-01-01
...ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH, AND CONSUMER INFORMATION Procedures... Definitions § 1220.608 Order. Order means the Soybean Promotion and Research...
Code of Federal Regulations, 2012 CFR
2012-01-01
...ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH, AND CONSUMER INFORMATION Procedures... Definitions § 1220.608 Order. Order means the Soybean Promotion and Research...
Code of Federal Regulations, 2014 CFR
2014-01-01
...ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH, AND CONSUMER INFORMATION Procedures... Definitions § 1220.608 Order. Order means the Soybean Promotion and Research...
Code of Federal Regulations, 2010 CFR
2010-01-01
...ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH, AND CONSUMER INFORMATION Procedures... Definitions § 1220.608 Order. Order means the Soybean Promotion and Research...
Code of Federal Regulations, 2013 CFR
2013-01-01
...ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SOYBEAN PROMOTION, RESEARCH, AND CONSUMER INFORMATION Procedures... Definitions § 1220.608 Order. Order means the Soybean Promotion and Research...
Tree reconstruction from partial orders
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.
Tree reconstruction from partial orders
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.
Order Symmetry of Weak Measurements
Lars M. Johansen; Pier A. Mello
2009-07-30
Weak values are usually associated with weak measurements of an observable on a pre- and post-selected ensemble. We show that more generally, weak values are proportional to the correlation between two pointers in a successive measurement. We show that this generalized concept of weak measurements displays a symmetry under reversal of measurement order. We show that the conditions for order symmetry are the same as in classical mechanics. We also find that the imaginary part of the weak value has a counterpart in classical mechanics. This scheme suggests new experimental possibilities.
NASA Astrophysics Data System (ADS)
Backman, M.; Juslin, N.; Nordlund, K.
2012-09-01
We develop an analytic bond order potential for modelling of gold. The bond order formalism includes bond angularity and offers an alternative approach to the embedded atom type potentials frequently used to describe metallic bonding. The advantage of the developed potential is that it can be extended to describe interactions with covalent materials. Experimental and ab initio data of gold properties is used to fit the potential and a good description of bulk and defect properties is achieved. We use the potential to simulate melting of nanoclusters and find that the experimentally observed size dependent melting behaviour is reproduced qualitatively.
Risk attitudes and birth order.
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
... the future. Talk to your doctor about the pros and cons of CPR. A DNR order may be a part of a hospice care plan. The focus of this care is not to prolong life, but to treat symptoms of pain or shortness ...
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)
NCI Mouse Repository - Ordering Information
Mouse models are provided free of charge through the NCI Mouse Repository, however, the customer is responsible for shipping charges if the shipment must go by air or special truck. There is no charge for normal truck delivery. Up to three (3) breeder pairs are routinely supplied on an order. On occasion, larger numbers of breeder pairs may be available - please inquire.
Executive Order 1083 Attachment C
Su, Xiao
Executive Order 1083 Attachment C California Child Abuse and Neglect Reporting Act Penal Code) An administrative officer or supervisor of child welfare and attendance, or a certificated pupil personnel employee, an administrator, or an employee of a licensed community care or child day care facility. (11) A Head Start program
Octupolar order in two dimensions.
Virga, Epifanio G
2015-06-01
Octupolar order is described in two space dimensions in terms of the maxima (and conjugated minima) of the probability density associated with a third-rank, fully symmetric and traceless tensor. Such a representation is shown to be equivalent to diagonalizing the relevant third-rank tensor, an equivalence which however is only valid in the two-dimensional case. PMID:26123766
Macrojunctions ordering in polyelectrolyte hydrogels
NASA Astrophysics Data System (ADS)
Török, Gy; Lebedev, V. T.; Cser, L.; Buyanov, A. L.; Revelskaya, L. G.
2000-03-01
We studied the structure of polyelectrolyte hydrogels of sodium polyacrylate cross-linked by macromolecular allyldextran (supergels). Using high-resolution SANS we have found the specific ordering of macrojunctions (structure's period ?130 nm) that may be reliable for the network's anomaly swelling.
Resplendent linear orders Andrey Bovykin #
Bovykin, Andrey
as many # 1 1 formulas as possible. Definition 1.3. An Lstructure M is chronically resplendentResplendent linear orders Andrey Bovykin # and Richard Kaye + June 14, 2002 Abstract This paper say. In this paper we are trying to characterize the notion of resplendency for certain theories
Resplendent linear orders Andrey Bovykin
Bovykin, Andrey
resplendent models satisfy as many 1 1-formulas as possible. Definition 1.3. An L-structure M is chronicallyResplendent linear orders Andrey Bovykin and Richard Kaye June 14, 2002 Abstract This paper language consistent with the elementary diagram of our model" and what they might say. In this paper we
PEMDAS: Algebraic Order of Operations
NSDL National Science Digital Library
2009-03-15
Watch this music video to help you learn about PEMDAS (Please Excuse My Dear Aunt Sally). Does this sound familiar? If not, this is an excellent device to memorize the algebraic order of operations. This video is produced by Mr. Davis Productions and plays music by Odyssey Sound Lab.
Magnetic ordering in iron tricyanomethanide.
Feyerherm, Ralf; Loose, Anja; Landsgesell, Sven; Manson, Jamie L
2004-10-18
Magnetic susceptibility, heat capacity, and neutron diffraction studies of Fe[C(CN)(3)](2) reveal the existence of two magnetic phase transitions at T(N,I) = 2.45 K and T(N,II) = 1.85 K. Between 1.85 and 2.45 K, the magnetic ordering is incommensurate with a temperature-dependent propagation vector (k(I,x) 0 0), k(I,x) = 0.525-0.540. In zero magnetic field, below 1.85 K the ordered structure is described by the propagation vector k(II) = ((1/2) 0 (1/2)), i.e., a doubling of the unit cell along the a and c directions of the orthorhombic lattice. The ordered moments of 3.4(1) and 3.2(1) micro(B), respectively, are aligned approximately parallel to the principal axis of the elongated Fe coordination octahedron. At T < T(N,II), application of an external magnetic field of about 18 kOe destroys the commensurate phase and the incommensurate phase is established. The latter phase is stable in fields up to about 40 kOe. The magnetic ordering of Fe[C(CN)(3)](2) is discussed in terms of the 2D triangular topology of the lattice, producing partial frustration, and in comparison with the behavior of other compounds of the series M[C(CN)(3)](2), where M is a 3d transition metal. PMID:15476361
Octupolar order in two dimensions
Epifanio G. Virga
2015-04-29
Octupolar order is described in two space dimensions in terms of the maxima (and conjugated minima) of the probability density associated with a third-rank, fully symmetric and traceless tensor. Such a representation is shown to be equivalent to diagonalizing the relevant third-rank tensor, an equivalence which however is only valid in the two-dimensional case.
Graded infinite order jet manifolds
G. Sardanashvily
2007-08-17
The relevant material on differential calculus on graded infinite order jet manifolds and its cohomology is summarized. This mathematics provides the adequate formulation of Lagrangian theories of even and odd variables on smooth manifolds in terms of the Grassmann-graded variational bicomplex.
Order computations in generic groups
Sutherland, Andrew V
2007-01-01
We consider the problem of computing the order of an element in a generic group. The two standard algorithms, Pollard's rho method and Shanks' baby-steps giant-steps technique, both use [theta](N^1/2) group operations to ...
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,…
Weighted order statistic classifiers with large rank-order margin.
Porter, R. B. (Reid B.); Hush, D. R. (Donald R.); Theiler, J. P. (James P.); Gokhale, M. (Maya)
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.
Code of Federal Regulations, 2012 CFR
2012-10-01
...issuance of an order under a task-order contract or delivery-order...delivery-order contracts or multiple task-order contracts, except as...Not use any method (such as allocation or designation of any preferred...exceeding $5 million . For task or delivery orders in...
Code of Federal Regulations, 2013 CFR
2013-10-01
...issuance of an order under a task-order contract or delivery-order...delivery-order contracts or multiple task-order contracts, except as...Not use any method (such as allocation or designation of any preferred...exceeding $5 million . For task or delivery orders in...
Code of Federal Regulations, 2014 CFR
2014-10-01
...issuance of an order under a task-order contract or delivery-order...delivery-order contracts or multiple task-order contracts, except as...Not use any method (such as allocation or designation of any preferred...exceeding $5 million. For task or delivery orders in...
Umbilic Lines in Orientational Order
Thomas Machon; Gareth P. Alexander
2015-07-31
Three-dimensional orientational order in systems whose ground states possess non-zero, chiral gradients typically exhibits line-like structures or defects: $\\lambda$ 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 generalisation of the umbilic points of a surface. We characterise these lines in terms of the natural vector bundles that the order defines and show that they give a way to localise and identify Skyrmion distortions in chiral materials -- in particular that they supply a natural representative of the Poincar\\'{e} 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.
Bayesian inferences on umbrella orderings.
Hans, Chris; Dunson, David B
2005-12-01
In regression applications with categorical predictors, interest often focuses on comparing the null hypothesis of homogeneity to an ordered alternative. This article proposes a Bayesian approach for addressing this problem in the setting of normal linear and probit regression models. The regression coefficients are assigned a conditionally conjugate prior density consisting of mixtures of point masses at 0 and truncated normal densities, with a (possibly unknown) changepoint parameter included to accommodate umbrella ordering. Two strategies of prior elicitation are considered: (1) a Bayesian Bonferroni approach in which the probability of the global null hypothesis is specified and local hypotheses are considered independent; and (2) an approach which treats these probabilities as random. A single Gibbs sampling chain can be used to obtain posterior probabilities for the different hypotheses and to estimate regression coefficients and predictive quantities either by model averaging or under the preferred hypothesis. The methods are applied to data from a carcinogenesis study. PMID:16401275
Recent advances in ordered intermetallics
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.
Ordering Juice Drinks (grade 4)
NSDL National Science Digital Library
2013-01-01
This is a sample PARCC assessment task based on CCSS grade 4 operations and algebraic thinking standards as well as the number and operations in base ten standards. In this interactive single task students must solve a multi-step problem by completing an order receipt for orange juice. Included are the alignments to the CCSS, a scoring rubric and background on the task itself.
Order stars and stability theorems
G. Wanner; E. Hairer; S. P. Nørsett
1978-01-01
This paper clears up to the following three conjectures:1.The conjecture of Ehle [1] on theA-acceptability of Padé approximations toez, which is true;2.The conjecture of Nørsett [5] on the zeros of the “E-polynomial”, which is false;3.The conjecture of Daniel and Moore [2] on the highest attainable order of certainA-stable multistep methods, which is true, generalizing the well-known Theorem of Dahlquist.
Chetan Nayak; R. B. Laughlin; Dirk Morr
2001-01-01
We propose that the enigmatic pseudogap phase of cuprate superconductors is characterized by a hidden broken symmetry of d_x^2-y^2-type. The transition to this state is rounded by disorder, but in the limit that the disorder is made sufficiently small, the pseudogap crossover should reveal itself to be such a transition. The ordered state breaks time-reversal, translational, and rotational symmetries, but
ATOM - Active Totally Ordered Multicast
Rory Graves; Ian Wakeman
2000-01-01
When group applications such as virtual environments, multiplayer games and battlefield simulations are distributed, they\\u000a generate communication needs that are not met by today’s communication infrastructure. The current Internet infrastructure\\u000a is built around point-to-point best effort packet switching design for unicast applications, whereas the above family of applications\\u000a require reliable, low latency, ordered multicast. The introduction of Active Networking resources
Ordered and chaotic spiral arms
NASA Astrophysics Data System (ADS)
Patsis, P. A.
2008-12-01
The stellar flow at the arms of spiral galaxies is qualitatively different among different morphological types. The stars that reinforce the spiral arms can be either participating in an ordered or in a chaotic flow. Ordered flows are associated with normal (non-barred) spiral galaxies. Typically they are described with precessing ellipses corresponding to stable periodic orbits at successive energies (Jacobi constants). On the contrary, the spiral arms in barred-spiral systems may be supported by stars in chaotic motion. The trajectories of these stars are associated with the invariant manifolds of the unstable Lagrangian points \\left(L1,2\\right). Response and orbital models indicate that this kind of spirals either stop at an azimuth smaller than \\pi/2, or present large gaps at about this angle. Chaotic spirals appear in strong bars having \\left(L1,2\\right) close to the ends of the bar. The arms of barred-spiral systems with corotation away from the end of the bar can be either as in the case of normal spirals, or supported by banana-like orbits surrounding the stable Lagrangian points \\left(L4,5\\right). We find also models combining ordered and chaotic flows.
Ben-Dor, Amir; Chor, Benny; Pelleg, Dan
2000-01-01
Radiation hybrid (RH) mapping is a somatic cell technique that is used for ordering markers along a chromosome and estimating the physical distances between them. With the advent of this mapping technique, analyzing the experimental data is becoming a challenging and demanding computational task. In this paper we present the software package RHO (radiation hybrid ordering). The package implements a number of heuristics that attempt to order genomic markers along a chromosome, given as input the results of an RH experiment. The heuristics are based on reducing an appropriate optimization problem to the traveling salesman problem (TSP). The reduced optimization problem is either the nonparametric obligate chromosome breaks (OCBs) or the parametric maximum likelihood estimation (MLE). We tested our package on both simulated and publicly available RH data. For synthetic RH data, the reconstructed markers' permutation is very close to the original permutation, even with fairly high error rates. For real data we used the framework markers' data from the Whitehead Institute maps. For most of the chromosomes (18 out of 23), there is a perfect agreement or nearly perfect agreement (reversal of chromosome arm or arms) between our maps and the Whitehead framework maps. For the remaining five chromosomes, our maps improve on the Whitehead framework maps with respect to both optimization criteria, having higher likelihood and fewer breakpoints. For three chromosomes, the results differ significantly (lod score >1.75), with chromosome 2 having the largest improvement (lod score 3.776). PMID:10720577
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.
Charge ordering and intermediate range order in ammonium ionic liquids
NASA Astrophysics Data System (ADS)
Siqueira, Leonardo J. A.; Ribeiro, Mauro C. C.
2011-11-01
Molecular dynamics simulations were performed for ionic liquids based on the bis(trifluoromethylsulfonyl)imide anion, [NTf2], and ammonium cations with increasing length of the alkyl chain and ether functionalized chain. The signature of charge ordering is a sharp peak in the charge-charge structure factor, Sqq(k), whose intensity is barely affected for longer carbon chain in tetraalkylammonium systems, but decreases in ether functionalized ionic liquids. The first sharp diffraction peak (FSDP) and the corresponding intermediate range order (IRO) are observed in the total S(k) of ionic liquids containing ammonium cations with relatively long chains. The intensity of the FSDP is lower in the total S(k) of the ether derivative in comparison with the tetraalkylammonium counterpart of the same chain length. It is shown that the nature of the IRO is structural heterogeneity of polar and non-polar domains, even though domains defined by chain interactions in the ether derivatives become more polar. Charge correlation in the ether derivative is modified because cations can be coordinated by oxygen atoms of the ether functionalized chain of neighboring cations.
Cation Ordering in Hydrous Wadsleyite
NASA Astrophysics Data System (ADS)
Holl, C. M.; Smyth, J. R.; Frost, D. J.
2006-12-01
Hydrous wadsleyite (?-Mg2SiO4) has been observed with monoclinic (I2/m) rather than orthorhombic (Imma). It has been proposed that the break in symmetry was due to ordering of cations on formerly equivalent M sites (Smyth et al., 1997) or various stacking arrangements of vacancy-bearing structural layers (Kudoh and Inoue, 1999). Cell parameters and structures of Fo100 wadsleyite samples with various water contents were refined from single-crystal X-ray diffraction data. Unit cell volume increases linearly with water content with volume of hydration of 0.17% per 1 wt% H2O. Structure refinements reveal nearly all cation vacancy occurs on M3, despite results from IR absorption spectroscopy studies (Kohn et al., 2002; Jacobsen et al., 2005) suggesting association of H with M1 and M2 sites. The most hydrous sample studied with 1.6 wt% H2O displayed monoclinic symmetry with ? = 90.1° and was refined in space group I2/m. The formerly equivalent M3 sites showed a difference in apparent scattering of 4? and a volume difference of 0.4%. If the two M3 sites differ significantly in compressibility, then hydrous wadsleyite at high PT conditions may possess strong cation ordering, with implications for the stability range in the mantle. Reports of ?-angle are inconsistent among samples with similar water contents, suggesting that the measured angle is highly sensitive to synthesis and quenching conditions. Rapid quenching may produce polysynthetically twinned samples with apparent near- orthorhombic symmetry. To determine the degree of ordering at high PT, synthesis experiments should be performed with long quenching times to maximize domain size.size.
Partial order of quantum effects
NASA Astrophysics Data System (ADS)
Lahti, Pekka J.; MaÌ§czynski, Maciej J.
1995-04-01
The set of effects is not a lattice with respect to its natural order. Projection operators do have the greatest lower bounds (and the least upper bounds) in that set, but there are also other (incomparable) effects which share this property. However, the coexistence, the commutativity, and the regularity of a pair of effects are not sufficient for the existence of their infima and suprema. The structure of the range of an observable (as a normalized POV measure) can vary from that of a commutative Boolean to a noncommutative non-Boolean subset of effects.
Crystalline order on the paraboloid
NASA Astrophysics Data System (ADS)
Giomi, Luca; Bowick, Mark
2006-03-01
We describe an experimental and theoretical investigation of crystalline order on a two-dimensional paraboloid. In contrast to the sphere, the paraboloid exhibits both variable Gaussian curvature and a boundary. Both these features must be treated for a thorough theoretical understanding. A macroscopic model of a parabolic crystal can be obtained in the laboratory by assembling a single layer of soap bubbles on the surface of a rotating liquid, thus extending the classic work of Bragg and Nye on planar arrays of soap bubbles.
The New International Economic Order
NASA Astrophysics Data System (ADS)
Streeten, Paul P.
1982-12-01
Starting from a premise of optimism, this paper first sets out the essence of the proposed New International Economic Order and then traces its origins and interpretations. It examines the options available for different groups of the developing countries and those open to the constructively-minded of the industrialized states. It also explores what avenues there might be for furthering common interests, for countering hidden biases which might be operating against developing states, and for avoiding unnecessary conflicts. The paper ends with a plea for the consideration of the higher interests both of the nation-state and of the human race.
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.
Aristomenis Donos; Jerome P. Gauntlett; Christiana Pantelidou
2013-10-21
We construct electrically charged, asymptotically $AdS_5$ black hole solutions that are dual to $d=4$ CFTs in a superfluid phase with either p-wave or $(p+ip)$-wave order. The two types of black holes have non-vanishing charged two-form in the bulk and appear at the same critical temperature in the unbroken phase. Both the p-wave and the $(p+ip)$-wave phase can be thermodynamically preferred, depending on the mass and charge of the two-form, and there can also be first order transitions between them. The p-wave black holes have a helical structure and some of them exhibit the phenomenon of pitch inversion as the temperature is decreased. Both the p-wave and the $(p+ip)$-wave black holes have zero entropy density ground states at zero temperature and we identify some new ground states which exhibit scaling symmetry, including a novel scenario for the emergence of conformal symmetry in the IR.
Ordering Phenomena in Undercooled Alloys
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].
Code of Federal Regulations, 2010 CFR
2010-07-01
...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 a respondent it...
Code of Federal Regulations, 2011 CFR
2011-07-01
...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 prohibits delivery...
Code of Federal Regulations, 2011 CFR
2011-01-01
...ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PORK PROMOTION, RESEARCH, AND CONSUMER INFORMATION Procedures...Definitions § 1230.610 Order. The term Order means the Pork Promotion, Research, and Consumer Information...
Code of Federal Regulations, 2013 CFR
2013-01-01
...ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PORK PROMOTION, RESEARCH, AND CONSUMER INFORMATION Procedures...Definitions § 1230.610 Order. The term Order means the Pork Promotion, Research, and Consumer Information...
Code of Federal Regulations, 2012 CFR
2012-07-01
...NONROAD COMPRESSION-IGNITION ENGINES Selective Enforcement Auditing § 89.503 Test orders. (a) A test order addressed...may not issue to a manufacturer more Selective Enforcement Auditing (SEA) test orders than an annual limit determined to be...
Code of Federal Regulations, 2014 CFR
2014-07-01
...NONROAD COMPRESSION-IGNITION ENGINES Selective Enforcement Auditing § 89.503 Test orders. (a) A test order addressed...may not issue to a manufacturer more Selective Enforcement Auditing (SEA) test orders than an annual limit determined to be...
Code of Federal Regulations, 2013 CFR
2013-07-01
...NONROAD COMPRESSION-IGNITION ENGINES Selective Enforcement Auditing § 89.503 Test orders. (a) A test order addressed...may not issue to a manufacturer more Selective Enforcement Auditing (SEA) test orders than an annual limit determined to be...
Code of Federal Regulations, 2011 CFR
2011-07-01
...NONROAD COMPRESSION-IGNITION ENGINES Selective Enforcement Auditing § 89.503 Test orders. (a) A test order addressed...may not issue to a manufacturer more Selective Enforcement Auditing (SEA) test orders than an annual limit determined to be...
Code of Federal Regulations, 2010 CFR
2010-01-01
...COMMODITIES), DEPARTMENT OF AGRICULTURE HONEY PACKERS AND IMPORTERS RESEARCH, PROMOTION...EDUCATION AND INDUSTRY INFORMATION ORDER Honey Packers and Importers Research, Promotion...1212.15 Order. “Order” means the Honey Packers and Importers Research,...
Recent advances in ordered intermetallics
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.
Ferromagnetic ordering in superatomic solids.
Lee, Chul-Ho; Liu, Lian; Bejger, Christopher; Turkiewicz, Ari; Goko, Tatsuo; Arguello, Carlos J; Frandsen, Benjamin A; Cheung, Sky C; Medina, Teresa; Munsie, Timothy J S; D'Ortenzio, Robert; Luke, Graeme M; Besara, Tiglet; Lalancette, Roger A; Siegrist, Theo; Stephens, Peter W; Crowther, Andrew C; Brus, Louis E; Matsuo, Yutaka; Nakamura, Eiichi; Uemura, Yasutomo J; Kim, Philip; Nuckolls, Colin; Steigerwald, Michael L; Roy, Xavier
2014-12-01
In order to realize significant benefits from the assembly of solid-state materials from molecular cluster superatomic building blocks, several criteria must be met. Reproducible syntheses must reliably produce macroscopic amounts of pure material; the cluster-assembled solids must show properties that are more than simply averages of those of the constituent subunits; and rational changes to the chemical structures of the subunits must result in predictable changes in the collective properties of the solid. In this report we show that we can meet these requirements. Using a combination of magnetometry and muon spin relaxation measurements, we demonstrate that crystallographically defined superatomic solids assembled from molecular nickel telluride clusters and fullerenes undergo a ferromagnetic phase transition at low temperatures. Moreover, we show that when we modify the constituent superatoms, the cooperative magnetic properties change in predictable ways. PMID:25379957
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.
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 -?
Code of Federal Regulations, 2014 CFR
2014-01-01
...AGRICULTURE SOFTWOOD LUMBER RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER Softwood Lumber Research, Promotion, Consumer Education, and Industry Information Order Definitions...
Code of Federal Regulations, 2013 CFR
2013-01-01
...AGRICULTURE SOFTWOOD LUMBER RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER Softwood Lumber Research, Promotion, Consumer Education, and Industry Information Order Definitions...
Fourth order spatial derivative gravity
Bemfica, F. S.; Gomes, M. [Instituto de Fisica, Universidade de Sao Paulo Caixa Postal 66318, 05315-970, Sao Paulo, SP (Brazil)
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.
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 Ho?ava-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.
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.
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.
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.
Taxogenomics of the order Chlamydiales.
Pillonel, Trestan; Bertelli, Claire; Salamin, Nicolas; Greub, Gilbert
2015-04-01
Bacterial classification is a long-standing problem for taxonomists and species definition itself is constantly debated among specialists. The classification of strict intracellular bacteria such as members of the order Chlamydiales mainly relies on DNA- or protein-based phylogenetic reconstructions because these organisms exhibit few phenotypic differences and are difficult to culture. The availability of full genome sequences allows the comparison of the performance of conserved protein sequences to reconstruct Chlamydiales phylogeny. This approach permits the identification of markers that maximize the phylogenetic signal and the robustness of the inferred tree. In this study, a set of 424 core proteins was identified and concatenated to reconstruct a reference species tree. Although individual protein trees present variable topologies, we detected only few cases of incongruence with the reference species tree, which were due to horizontal gene transfers. Detailed analysis of the phylogenetic information of individual protein sequences (i) showed that phylogenies based on single randomly chosen core proteins are not reliable and (ii) led to the identification of twenty taxonomically highly reliable proteins, allowing the reconstruction of a robust tree close to the reference species tree. We recommend using these protein sequences to precisely classify newly discovered isolates at the family, genus and species levels. PMID:25634949
46 CFR Sec. 7 - Job order numbering.
Code of Federal Regulations, 2013 CFR
2013-10-01
...2013-10-01 2013-10-01 false Job order numbering. Sec. 7 Section 7...REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 7 Job order numbering. (a) The NSA-LUMPSUMREP...Contract number shall be inserted in every job order and supplemental job order...
46 CFR Sec. 7 - Job order numbering.
Code of Federal Regulations, 2011 CFR
2011-10-01
...2011-10-01 2011-10-01 false Job order numbering. Sec. 7 Section 7...REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 7 Job order numbering. (a) The NSA-LUMPSUMREP...Contract number shall be inserted in every job order and supplemental job order...
46 CFR Sec. 7 - Job order numbering.
Code of Federal Regulations, 2014 CFR
2014-10-01
...2014-10-01 2014-10-01 false Job order numbering. Sec. 7 Section 7...REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 7 Job order numbering. (a) The NSA-LUMPSUMREP...Contract number shall be inserted in every job order and supplemental job order...
46 CFR Sec. 7 - Job order numbering.
Code of Federal Regulations, 2012 CFR
2012-10-01
...2012-10-01 2012-10-01 false Job order numbering. Sec. 7 Section 7...REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 7 Job order numbering. (a) The NSA-LUMPSUMREP...Contract number shall be inserted in every job order and supplemental job order...
Exploring Higher-Order Gravitational Waves
H. Arcos; M. Krssak; J. G. Pereira
2015-04-29
In addition to the usual linear gravitational waves in transverse-traceless coordinates, higher-order gravitational field equations, as well as their corresponding solutions, are explicitly obtained. It is found that higher-order waves do not represent corrections to the first-order wave. In contrast, all higher than second-order solutions do represent corrections to the second-order wave, a property that makes the first-order gravitational wave to stand apart from higher-order waves. Furthermore, although the first-order solution is transverse and traceless, all higher-order solutions are not. As a consequence, the whole solution is neither transverse nor traceless, a result that could eventually have important consequences for quantum gravity, and in particular for the definition of graviton itself. Some additional properties and features of these higher-order gravitational waves are explored and discussed.
Exploring Higher-Order Gravitational Waves
Arcos, H; Pereira, J G
2015-01-01
In addition to the usual linear gravitational waves in transverse-traceless coordinates, higher-order gravitational field equations, as well as their corresponding solutions, are explicitly obtained. It is found that higher-order waves do not represent corrections to the first-order wave. In contrast, all higher than second-order solutions do represent corrections to the second-order wave, a property that makes the first-order gravitational wave to stand apart from higher-order waves. Furthermore, although the first-order solution is transverse and traceless, all higher-order solutions are not. As a consequence, the whole solution is neither transverse nor traceless, a result that could eventually have important consequences for quantum gravity, and in particular for the definition of graviton itself. Some additional properties and features of these higher-order gravitational waves are explored and discussed.
Visual perception of order-disorder transition
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
Code of Federal Regulations, 2011 CFR
2011-10-01
...DEPARTMENT OF COMMERCE CONTRACTING METHODS AND CONTRACT TYPES TYPES OF CONTRACTS Indefinite-Delivery Contracts 1316.505 Ordering. The department's Task and Delivery Order Ombudsman is designated in CAM...
Code of Federal Regulations, 2014 CFR
2014-10-01
...DEPARTMENT OF COMMERCE CONTRACTING METHODS AND CONTRACT TYPES TYPES OF CONTRACTS Indefinite-Delivery Contracts 1316.505 Ordering. The department's Task and Delivery Order Ombudsman is designated in CAM...
Code of Federal Regulations, 2010 CFR
2010-10-01
...DEPARTMENT OF COMMERCE CONTRACTING METHODS AND CONTRACT TYPES TYPES OF CONTRACTS Indefinite-Delivery Contracts 1316.505 Ordering. The department's Task and Delivery Order Ombudsman is designated in CAM...
Code of Federal Regulations, 2012 CFR
2012-10-01
...DEPARTMENT OF COMMERCE CONTRACTING METHODS AND CONTRACT TYPES TYPES OF CONTRACTS Indefinite-Delivery Contracts 1316.505 Ordering. The department's Task and Delivery Order Ombudsman is designated in CAM...
Petroleum: The Petroleum (Carbon Disulphide) Order, 1958
Agnew, W.G.
1958-01-01
The Order in Council now revoked by Article 2 of this Order when originally made applied to bisulphide of carbon the provisions of the Acts repealed and replaced by the Petroleum (Consolidation) Act, 1928, relating to the ...
Code of Federal Regulations, 2010 CFR
2010-10-01
...issued” when the Government deposits the order in the mail. Orders may be issued orally, by facsimile, or by electronic commerce methods only if authorized in the Schedule. (End of clause) [60 FR 49727, Sept. 26,...
22 CFR 521.24 - Protective order.
Code of Federal Regulations, 2010 CFR
2010-04-01
...2010-04-01 true Protective order. 521.24 Section 521.24 Foreign Relations BROADCASTING...PROGRAM FRAUD CIVIL REMEDIES ACT § 521.24 Protective order...limited to certain matters; (5) That discovery be conducted...
CHEMICAL, MAGNETIC AND CHARGE ORDERING IN THE
Burton, Benjamin P.
in chemical and magnetic order- ing(Ishikawa and Akimoto, 1957; Ishikawa, 1958). In Fe2O3, iron has a nominal diagram (Burton and Davidson, 1988; Ghiorso, 1997), Fig. 1, exhibits: a chemical order-disorder transition
/. --LONG RANGE ORDER --EXTENDED DEFECTS --NON STOICHIOMETRY.
Boyer, Edmond
transitions in solids. Particular attention is paid to the relation with crystallographic defects/. -- LONG RANGE ORDER -- EXTENDED DEFECTS -- NON STOICHIOMETRY. ELECTRON MICROSCOPY POTENTIALITIES of respectively shear, crystallographic shear, order-disorqer and displacive transformations. The study
39 CFR 952.30 - Supplemental orders.
Code of Federal Regulations, 2011 CFR
2011-07-01
...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 Postal Inspector or...
39 CFR 952.30 - Supplemental orders.
Code of Federal Regulations, 2010 CFR
2010-07-01
...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 her designee or his...
On the order of general linear methods.
Constantinescu, E. M.; Mathematics and Computer Science
2009-09-01
General linear (GL) methods are numerical algorithms used to solve ODEs. The standard order conditions analysis involves the GL matrix itself and a starting procedure; however, a finishing method (F) is required to extract the actual ODE solution. The standard order analysis and stability are sufficient for the convergence of any GL method. Nonetheless, using a simple GL scheme, we show that the order definition may be too restrictive. Specifically, the order for GL methods with low order intermediate components may be underestimated. In this note we explore the order conditions for GL schemes and propose a new definition for characterizing the order of GL methods, which is focused on the final result--the outcome of F--and can provide more effective algebraic order conditions.
Code of Federal Regulations, 2014 CFR
2014-07-01
...CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM MARINE SPARK-IGNITION ENGINES Selective Enforcement Auditing Regulations § 91.604 Test orders. (a) A test order addressed to the manufacturer is required for any testing...
Code of Federal Regulations, 2013 CFR
2013-07-01
...CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM MARINE SPARK-IGNITION ENGINES Selective Enforcement Auditing Regulations § 91.604 Test orders. (a) A test order addressed to the manufacturer is required for any testing...
Prioritization and control of order picking system
Kanburapa, Prachyathit
2013-01-01
Order Picking System (OPS) efficiency at a warehouse was studied with the goal of reducing production order lead time to 8 hours. Current material flow system and strategy were studied through interviews with personnel ...
46 CFR 550.201 - Information orders.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Information orders. 550.201 Section 550.201...SHIPPING IN THE FOREIGN TRADE OF THE UNITED STATES Production of Information § 550.201 Information orders. In furtherance of the...
First order formulation of unimodular gravity
NASA Astrophysics Data System (ADS)
Álvarez, E.; González-Martín, S.
2015-07-01
First order Lagrangians for the Weyl invariant formulation of unimodular gravity are proposed. Several alternatives are examined; in some of them, first and second order are equivalent in a certain gauge only.
Decidable Expansions of Labelled Linear Orderings
Bès, Alexis
2011-01-01
Let $M=(A,<,\\overline{P})$ where $(A,<)$ is a linear ordering and $\\overline{P}$ denotes a finite sequence of monadic predicates on $A$. We show that if $A$ contains an interval of order type $\\omega$ or $-\\omega$, and the monadic second-order theory of $M$ is decidable, then there exists a non-trivial expansion $M'$ of $M$ by a monadic predicate such that the monadic second-order theory of $M'$ is still decidable.
Source of second order chromaticity in RHIC
Luo, Y.; Gu, X.; Fischer, W.; Trbojevic, D.
2011-01-01
In this note we will answer the following questions: (1) what is the source of second order chromaticities in RHIC? (2) what is the dependence of second order chromaticity on the on-momentum {beta}-beat? (3) what is the dependence of second order chromaticity on {beta}* at IP6 and IP8? To answer these questions, we use the perturbation theory to numerically calculate the contributions of each quadrupole and sextupole to the first, second, and third order chromaticities.
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.
On perfect order subsets in finite groups
Nguyen Trong Tuan; Bui Xuan Hai
2010-01-01
If $G$ is a finite group and $x\\\\in G$ then the set of all elements of $G$ having the same order as $x$ is called {\\\\em an order subset of $G$ determined by $x$} (see [2]). We say that $G$ is a {\\\\em group with perfect order subsets} or briefly, $G$ is a {\\\\em $POS$-group} if the number of elements
Ordering Tax Transcripts A. Online Request
Wagner, Diane
Ordering Tax Transcripts A. Online Request Go to: www.irs.gov In the "Online Services" section, select "Order a Tax Return or Account Transcript". Click "Order a Transcript" Provide tax filer's SSN "Return Transcript" and the appropriate year in "Tax Year" field. If successfully linked, tax filers can
Graph Structure Learning for Task Ordering
Yiming Yang; Abhimanyu Lad; Henry Shu; Bryan Kisiel; Chad M. Cumby; Rayid Ghani; Katharina Probst
2009-01-01
In many practical applications, multiple interrelated tasks must be accomplished sequentially through user interaction with retrieval, classification and recommendation systems. The ordering of the tasks may have a significant impact on the overall utility (or performance) of the systems; hence optimal ordering of tasks is desirable. However, manual specification of optimal ordering is often difficult when task dependencies are complex,
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…
AIAA 99--1467 LOW ORDER AERODYNAMIC
Peraire, Jaime
AIAA 99--1467 LOW ORDER AERODYNAMIC MODELS FOR AEROELASTIC CONTROL OF TURBOMACHINES K.E. Willcox, J of Aeronautics and Astronautics 1801 Alexander Bell Drive, Suite 500, Reston, VA 22091 #12; LOW ORDER AERODYNAMIC order aerodynamic model is developed for aeroelastic analysis of turbomachines. The proper or thogonal
49 CFR 1503.425 - Compromise orders.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Compromise orders. 1503.425 Section 1503...Civil Penalties by TSA § 1503.425 Compromise orders. (a) Issuance. ...dispose of the case by the issuance of a compromise order by TSA. (b) Contents....
TIGHT BOUNDS ON EXPECTED ORDER STATISTICS
Bertsimas, Dimitris
TIGHT BOUNDS ON EXPECTED ORDER STATISTICS DIIIMMMIIITTTRRRIIISSS BEEERRRTTTSSSIIIMMMAAASSS Sloan@nus.edu.sg In this article, we study the problem of finding tight bounds on the expected value of the kth-order statistic E of the highest-order statistic E @Xn:n# can be computed with a bisection search algo- rithm+ An extremal discrete
Higher Education Guidelines for Executive Order 11246.
ERIC Educational Resources Information Center
Office for Civil Rights (DHEW), Washington, DC.
This document presents and explains Executive Order 11246, the order prohibiting discrimination under federal contracts in colleges and universities. Part one of the document describes the legal provisions of the order; part two deals with personnel policies and practices including recruitment, hiring, anti-nepotism policies, training, promotion,…
Orderings, excess functions, and the nucleolus
Jean Derks; Hans Peters
1998-01-01
The nucleolus of a cooperative game can be described with the aid of the leximin ordering but also on the basis of two other orderings. In this note the relation between these orderings is studied in a more general framework. The results are applied to the nucleolus corresponding to so-called normal excess functions. Also the Kohlberg criterion is extended to
Comparing the Pairing Efficiency over Composite-Order and Prime-Order Elliptic
International Association for Cryptologic Research (IACR)
Comparing the Pairing Efficiency over Composite-Order and Prime-Order Elliptic Curves Aurore composite-order and prime-order elliptic curves. Composite orders must be large enough to be infeasible to factor. They are modulus of 2 up to 5 large prime numbers in the literature. There exists size recommen
Converting Pairing-Based Cryptosystems from Composite-Order Groups to Prime-Order Groups
International Association for Cryptologic Research (IACR)
Converting Pairing-Based Cryptosystems from Composite-Order Groups to Prime-Order Groups David pairing-based cryptosystems, and we show how to use prime-order elliptic curve groups to construct, and/or related assumptions in prime-order groups. We apply our framework and our prime-order group
Tools for Simulating Features of Composite Order Bilinear Groups in the Prime Order Setting
International Association for Cryptologic Research (IACR)
Tools for Simulating Features of Composite Order Bilinear Groups in the Prime Order Setting Allison a general methodology for converting composite order pairing- based cryptosystems into the prime order assumption, and will result in prime order schemes that are proven secure from the decisional linear
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.
Code of Federal Regulations, 2010 CFR
2010-01-01
...Amending Executive Order 12425 Designating Interpol as a Public International Organization...Amending Executive Order 12425 Designating Interpol as a Public International Organization...International Criminal Police Organization (INTERPOL), it is hereby ordered that...
Wanakule, Nisita S.; Panday, Ashoutosh; Mullin, Scott A.; Gann, Eliot; Hexemer, Alex; Balsara, Nitash P.; (UCB); (LBNL)
2009-09-15
Order-order and order-disorder phase transitions in mixtures of poly(styrene-block-ethylene oxide) (SEO) copolymers and lithium bis(trifluoromethylsulfonimide) (LiTFSI), a common lithium salt used in polymer electrolytes, were studied using a combination of small-angle X-ray scattering (SAXS), birefringence, and ac impedance spectroscopy. The SEO/LiTFSI mixtures exhibit lamellar, hexagonally packed cylinders, and gyroid microphases. The molecular weight of the blocks and the salt concentration was adjusted to obtain order-order and order-disorder transition temperatures within the available experimental window. The ionic conductivities of the mixtures, normalized by the ionic conductivity of a 20 kg/mol homopolymer PEO sample at the salt concentration and temperature of interest, were independent of temperature, in spite of the presence of the above-mentioned phase transitions.
Control of Initialized Fractional-Order Systems
NASA Technical Reports Server (NTRS)
Hartly, Tom T.; Lorenzo, Carl F.
2002-01-01
Due to the importance of historical effects in fractional-order systems, this paper presents a general fractional-order control theory that includes the time-varying initialization response. Previous studies have not properly accounted for these historical effects. The initialization response, along with the forced response, for fractional-order systems is determined. Stability properties of fractional-order systems are presented in the complex Airplane, which is a transformation of the s-plane. Time responses are discussed with respect to pole positions in the complex Airplane and frequency response behavior is included. A fractional-order vector space representation, which is a generalization of the state space concept, is presented including the initialization response. Control methods for vector representations of initialized fractional-order systems are shown. Nyquist, root-locus, and other input-output control methods are adapted to the control of fractional-order systems. Finally, the fractional-order differintegral is generalized to continuous order-distributions that have the possibility of including a continuum of fractional orders in a system element.
Net order optimization in analog net bundles
NASA Astrophysics Data System (ADS)
Jambor, Thomas; Schreiner, Lars; Olbrich, Markus; Barke, Erich
2005-06-01
This paper presents a new approach to optimize net order in analog busses. It is used for the PARasitic SYmmetric router (PARSY), which routes net bundles, e.g. busses or differential pairs, maintaining parasitic symmetry and limiting differential coupling. The router is mainly devoted to analog signal interconnect but can also be used for critical digital busses. Net bundles have a fixed order, because wire crossing is not allowed in net bundle segments to enforce symmetry. Wires inside net bundle segments are generated by module generators. Connecting cell terminals to the first or the last net bundle segment is complex, because the cell terminals can vary in geometry and placement. Therefore, an assignment between nets and wires (net order) in a segment is required. This assignment does not affect the order in which nets or net bundles are routed sequentially. The optimization objective for the connections from net bundle segments to terminals is to minimize the number of crossings and the length difference, while maintaining symmetry if possible. Therefore, a net order has to be calculated, which globally optimizes these criteria for all terminal connections. Different net orders can be computed from the placement of terminals, which have to be connected to a net bundle segment. An additional order is calculated from these net orders, which contains the most characteristic features of all net orders. For all net orders costs are evaluated, and the one with the lowest cost is chosen.
Order Parameters for Two-Dimensional Networks
NASA Astrophysics Data System (ADS)
Kaatz, Forrest; Bultheel, Adhemar; Egami, Takeshi
2007-10-01
We derive methods that explain how to quantify the amount of order in ``ordered'' and ``highly ordered'' porous arrays. Ordered arrays from bee honeycomb and several from the general field of nanoscience are compared. Accurate measures of the order in porous arrays are made using the discrete pair distribution function (PDF) and the Debye-Waller Factor (DWF) from 2-D discrete Fourier transforms calculated from the real-space data using MATLAB routines. An order parameter, OP3, is defined from the PDF to evaluate the total order in a given array such that an ideal network has the value of 1. When we compare PDFs of man-made arrays with that of our honeycomb we find OP3=0.399 for the honeycomb and OP3=0.572 for man's best hexagonal array. The DWF also scales with this order parameter with the least disorder from a computer-generated hexagonal array and the most disorder from a random array. An ideal hexagonal array normalizes a two-dimensional Fourier transform from which a Debye-Waller parameter is derived which describes the disorder in the arrays. An order parameter S, defined by the DWF, takes values from [0, 1] and for the analyzed man-made array is 0.90, while for the honeycomb it is 0.65. This presentation describes methods to quantify the order found in these arrays.
Synchronization of chaotic systems with different order.
Femat, Ricardo; Solís-Perales, Gualberto
2002-03-01
The chaotic synchronization of third-order systems and second-order driven oscillator is studied in this paper. Such a problem is related to synchronization of strictly different chaotic systems. We show that dynamical evolution of second-order driven oscillators can be synchronized with the canonical projection of a third-order chaotic system. In this sense, it is said that synchronization is achieved in reduced order. Duffing equation is chosen as slave system whereas Chua oscillator is defined as master system. The synchronization scheme has nonlinear feedback structure. The reduced-order synchronization is attained in a practical sense, i.e., the difference e=x(3)-x(1)(') is close to zero for all time t> or =t(0)> or =0, where t(0) denotes the time of the control activation. PMID:11909231
Variable-order fuzzy fractional PID controller.
Liu, Lu; Pan, Feng; Xue, Dingyu
2015-03-01
In this paper, a new tuning method of variable-order fractional fuzzy PID controller (VOFFLC) is proposed for a class of fractional-order and integer-order control plants. Fuzzy logic control (FLC) could easily deal with parameter variations of control system, but the fractional-order parameters are unable to change through this way and it has confined the effectiveness of FLC. Therefore, an attempt is made in this paper to allow all the five parameters of fractional-order PID controller vary along with the transformation of system structure as the outputs of FLC, and the influence of fractional orders ? and ? on control systems has been investigated to make the fuzzy rules for VOFFLC. Four simulation results of different plants are shown to verify the availability of the proposed control strategy. PMID:25440947
Magid, S.; Forrer, C.; Shaha, S.
2012-01-01
Objective Computerized provider/physician order entry (CPOE) with clinical decision support (CDS) is designed to improve patient safety. However, a number of unintended consequences which include duplicate ordering have been reported. The objective of this time-series study was to characterize duplicate orders and devise strategies to minimize them. Methods Time series design with systematic weekly sampling for 84 weeks. Each week we queried the CPOE database, downloaded all active orders onto a spreadsheet, and highlighted duplicate orders. We noted the following details for each duplicate order: time, order details (e.g. drug, dose, route and frequency), ordering prescriber, including position and role, and whether the orders originated from a single order or from an order set (and the name of the order set). This analysis led to a number of interventions, including changes in: order sets, workflow, prescriber training, pharmacy procedures, and duplicate alerts. Results Duplicates were more likely to originate from different prescribers than from same prescribers; and from order sets than from single orders. After interventions, there was an 84.8% decrease in the duplication rate from weeks 1 to 84 and a 94.6% decrease from the highest (1) to the lowest week (75). Currently, we have negligible duplicate orders. Conclusions Duplicate orders can be a significant unintended consequence of CPOE. By analyzing these orders, we were able to devise and implement generalizable strategies that significantly reduced them. The incidence of duplicate orders before CPOE implementation is unknown, and our data originate from a weekly snapshot of active orders, which serves as a sample of total active orders. Thus, it should be noted that this methodology likely under-reports duplicate orders. PMID:23646085
Critical higher order gravities in higher dimensions
NASA Astrophysics Data System (ADS)
Kan, Nahomi; Kobayashi, Koichiro; Shiraishi, Kiyoshi
2013-08-01
We show that the higher order gravity model proposed by Meissner and Olechowski has a graviton mode, a massive spin-two excitation, and no scalar mode in a maximally symmetric spacetime; therefore, by choosing the coefficients, we can construct a Lagrangian for “critical gravity” from higher order terms of curvatures in higher dimensions. We also give a comment on construction of the theory with multicriticality in higher order gravities.
Order-memory and association-memory.
Caplan, Jeremy B
2015-09-01
Two highly studied memory functions are memory for associations (items presented in pairs, such as SALT-PEPPER) and memory for order (a list of items whose order matters, such as a telephone number). Order- and association-memory are at the root of many forms of behaviour, from wayfinding, to language, to remembering people's names. Most researchers have investigated memory for order separately from memory for associations. Exceptions to this, associative-chaining models build an ordered list from associations between pairs of items, quite literally understanding association- and order-memory together. Alternatively, positional-coding models have been used to explain order-memory as a completely distinct function from association-memory. Both classes of model have found empirical support and both have faced serious challenges. I argue that models that combine both associative chaining and positional coding are needed. One such hybrid model, which relies on brain-activity rhythms, is promising, but remains to be tested rigourously. I consider two relatively understudied memory behaviours that demand a combination of order- and association-information: memory for the order of items within associations (is it William James or James William?) and judgments of relative order (who left the party earlier, Hermann or William?). Findings from these underexplored procedures are already difficult to reconcile with existing association-memory and order-memory models. Further work with such intermediate experimental paradigms has the potential to provide powerful findings to constrain and guide models into the future, with the aim of explaining a large range of memory functions, encompassing both association- and order-memory. (PsycINFO Database Record PMID:25894964
Destruction of bulk ordering by surface randomness
D. E. Feldman; V. M. Vinokur
2002-06-18
We demonstrate that the arbitrarily weak quenched disorder on the surface of a system of continuous symmetry destroys long range order in the bulk, and, instead, quasi-long range order emerges. Correlation functions are calculated exactly for the two- and three-dimensional XY model with surface randomness via the functional renormalization group. Even at strong quenched disorder the three-dimensional XY model possesses topological order. We also determine roughness of a domain wall in the presence of surface disorder.
A characteristic signature of fourth order gravity
Kishore N. Ananda; Sante Carloni; Peter K. S. Dunsby
2008-12-10
We present for the first time the complete matter power spectrum for $R^n$ gravity which has been derived from the fourth order scalar perturbation equations. This leads to the discovery of a characteristic signature of fourth order gravity in the matter power spectrum, the details of which have not seen before in other studies in this area and therefore provides a crucial test for fourth order gravity on cosmological scales.
A characteristic signature of fourth order gravity
Ananda, Kishore N; Dunsby, Peter K S
2008-01-01
We present for the first time the complete matter power spectrum for $R^n$ gravity which has been derived from the fourth order scalar perturbation equations. This leads to the discovery of a characteristic signature of fourth order gravity in the matter power spectrum, the details of which have not seen before in other studies in this area and therefore provides a crucial test for fourth order gravity on cosmological scales.
Optical method of atomic ordering estimation
Prutskij, T.; Attolini, G.
2013-12-04
It is well known that within metal-organic vapor-phase epitaxy (MOVPE) grown semiconductor III-V ternary alloys atomically ordered regions are spontaneously formed during the epitaxial growth. This ordering leads to bandgap reduction and to valence bands splitting, and therefore to anisotropy of the photoluminescence (PL) emission polarization. The same phenomenon occurs within quaternary semiconductor alloys. While the ordering in ternary alloys is widely studied, for quaternaries there have been only a few detailed experimental studies of it, probably because of the absence of appropriate methods of its detection. Here we propose an optical method to reveal atomic ordering within quaternary alloys by measuring the PL emission polarization.
Pi Bond Orders and Bond Lengths
ERIC Educational Resources Information Center
Herndon, William C.; Parkanyi, Cyril
1976-01-01
Discusses three methods of correlating bond orders and bond lengths in unsaturated hydrocarbons: the Pauling theory, the Huckel molecular orbital technique, and self-consistent-field techniques. (MLH)
Resonant radiation from oscillating higher order solitons.
Driben, R; Yulin, A V; Efimov, A
2015-07-27
We present radiation mechanism exhibited by a higher order soliton. In a course of its evolution the higher-order soliton emits polychromatic radiation resulting in formation of multipeak frequency comb-like spectral band. The shape and spectral position of this band can be effectively controlled by the relative strength of the third order dispersion. An analytical description is corroborated by numerical simulations. It is shown that for longer pulses the described effect persists also under the action of higher order perturbations such as Raman and self-steepening. PMID:26367574
Higher order mechanics on graded bundles
Andrew James Bruce; Katarzyna Grabowska; Janusz Grabowski
2014-12-09
In this paper we develop a geometric approach to higher order mechanics on graded bundles in both, the Lagrangian and Hamiltonian formalism, via the recently discovered weighted algebroids. We present the corresponding Tulczyjew triple for this higher order situation and derive in this framework the phase equations from an arbitrary (also singular) Lagrangian or Hamiltonian, as well as the Euler-Lagrange equations. As important examples, we geometrically derive the classical higher order Euler-Lagrange equations and analogous reduced equations for invariant higher order Lagrangians on Lie groupoids.
CCII based fractional filters of different orders
Soltan, Ahmed; Radwan, Ahmed G.; Soliman, Ahmed M.
2013-01-01
This paper aims to generalize the design of continuous-time filters to the fractional domain with different orders and validates the theoretical results with two different CCII based filters. In particular, the proposed study introduces the generalized formulas for the previous fractional-order analysis of equal orders. The fractional-order filters enhance the design flexibility and prove that the integer-order performance is a very narrow subset from the fractional-order behavior due to the extra degrees of freedom. The general fundamentals of these filters are presented by calculating the maximum and minimum frequencies, the half power frequency and the right phase frequency which are considered a critical issue for the filter design. Different numerical solutions for the generalized fractional order low pass filters with two different fractional order elements are introduced and verified by the circuit simulations of two fractional-order filters: Kerwin–Huelsman–Newcomb (KHN) and Tow-Tomas CCII-based filters, showing great matching. PMID:25685483
Chaos in a Fractional Order Chua System
NASA Technical Reports Server (NTRS)
Lorenzo, Carl F.; Hartley, Tom T.; Qammar, Helen Killory
1996-01-01
This report studies the effects of fractional dynamics in chaotic systems. In particular, Chua's system is modified to include fractional order elements. Varying the total system order incrementally from 2.6 to 3.7 demonstrates that systems of 'order' less than three can exhibit chaos as well as other nonlinear behavior. This effectively forces a clarification of the definition of order which can no longer be considered only by the total number of differentiations or by the highest power of the Laplace variable.
Paths and stochastic order in open systems
Lucia, Umberto
2011-01-01
The principle of maximum irreversible is proved to be a consequence of a stochastic order of the paths inside the phase space; indeed, the system evolves on the greatest path in the stochastic order. The result obtained is that, at the stability, the entropy generation is maximum and, this maximum value is consequence of the stochastic order of the paths in the phase space, while, conversely, the stochastic order of the paths in the phase space is a consequence of the maximum of the entropy generation at the stability.
Higher order mechanics on graded bundles
NASA Astrophysics Data System (ADS)
Bruce, Andrew James; Grabowska, Katarzyna; Grabowski, Janusz
2015-05-01
In this paper we develop a geometric approach to higher order mechanics on graded bundles in both, the Lagrangian and Hamiltonian formalism, via the recently discovered weighted algebroids. We present the corresponding Tulczyjew triple for this higher order situation and derive in this framework the phase equations from an arbitrary (also singular) Lagrangian or Hamiltonian, as well as the Euler–Lagrange equations. As important examples, we geometrically derive the classical higher order Euler–Lagrange equations and analogous reduced equations for invariant higher order Lagrangians on Lie groupoids.
Resonant radiation from oscillating higher order solitons
Driben, R.; Yulin, A. V.; Efimov, A.
2015-07-15
We present radiation mechanism exhibited by a higher order soliton. In a course of its evolution the higher-order soliton emits polychromatic radiation resulting in formation of multipeak frequency comb-like spectral band. The shape and spectral position of this band can be effectively controlled by the relative strength of the third order dispersion. An analytical description is corroborated by numerical simulations. Research showed that for longer pulses the described effect persists also under the action of higher order perturbations such as Raman and self-steepening.
Ordered Rate Constitutive Theories in Eulerian Description
Nunez, Daniel
2012-12-31
This research work presents development of ordered rate constitutive theories in Eulerian description for homogeneous, isotropic, compressible and incompressible matter experiencing finite deformation using contravariant, ...
Code of Federal Regulations, 2013 CFR
2013-01-01
...IMPORTERS RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER...Importers Research, Promotion, Consumer Education, and Industry Information...Importers Research, Promotion, Consumer Education and Industry Information...
Code of Federal Regulations, 2011 CFR
2011-01-01
...IMPORTERS RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER...Importers Research, Promotion, Consumer Education, and Industry Information...Importers Research, Promotion, Consumer Education and Industry Information...
Code of Federal Regulations, 2012 CFR
2012-01-01
...IMPORTERS RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER...Importers Research, Promotion, Consumer Education, and Industry Information...Importers Research, Promotion, Consumer Education and Industry Information...
Code of Federal Regulations, 2014 CFR
2014-01-01
...IMPORTERS RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER...Importers Research, Promotion, Consumer Education, and Industry Information...Importers Research, Promotion, Consumer Education and Industry Information...
On the dynamics of (left) orderable groups
Navas, Andres
2007-01-01
We study left orderable groups by using dynamical methods. We apply these techniques to study the space of orederings of those groups. We show for instance that for the case of (non-abelian) free groups, this space is homeomorphic to the Cantor set. We also stydy the case of braid groups (for which the space of orderings has isolated points but contains homeomorphic copies of the Cantor set). To do this we introduce the notion of the conradian soul of an order as the maximal subgroup which is convex and restricted to which the original ordering satisfies the so called conradian property, and we elaborate on this notion.
Second Order Vector Perturbations on Bouncing Universes
NASA Astrophysics Data System (ADS)
Mena, F. C.
Considering inflationary, ekpyrotic and “dust-like” models we have shown that second order vector perturbations provide new distinguishing observational features between those early univese scenarios.
STUDENTS BOOK CORPORATION and CRIMSON AND GRAY FACULTY TEXTBOOK ORDER SHEET First Order
Collins, Gary S.
TEXTBOOK ORDER SHEET First Order 6/10/09 Fall Semester 2009 Department of Physics & Astronomy AUTHORSTUDENTS BOOK CORPORATION and CRIMSON AND GRAY FACULTY TEXTBOOK ORDER SHEET First Order 6/10/09 Fall Semester 2009 Department of Physics & Astronomy AUTHOR TITLE VOL/ED. DATE P/ C PUBLISHER CLASS SEC
75 FR 32846 - Final Rule Relating to Time and Order of Issuance of Domestic Relations Orders
Federal Register 2010, 2011, 2012, 2013, 2014
2010-06-10
...Issuance of Domestic Relations Orders AGENCY: Employee...Protection Act of 2006, Public Law No. [[Page 32847...and order of domestic relations orders under section...no longer meets the definition of ``surviving spouse...receives a domestic relations order requiring...
Title Format and Order Type AAS History Series Print; Serial Standing Order
Clayton, Dale H.
Title Format and Order Type AAS History Series Print; Serial Standing Order Advanced Series in Astrophysics and Cosmology Continuation/Print Monograph Standing Order Akzente Print, Serial Alexander Lectures Continuation/Print Monograph Standing Order, Discontinued? Annales de démographie historique Print, Serial
70 FR 29388 - Winter Pears Grown in Oregon and Washington; Order Amending Marketing Order No. 927
Federal Register 2010, 2011, 2012, 2013, 2014
2005-05-20
...7 CFR Part 927 Winter Pears Grown in Oregon and Washington; Order...V-927-A1; FV04-927-1 FR] Winter Pears Grown in Oregon and Washington; Order...the marketing order (order) for winter pears grown in Oregon and Washington. The...
Second-order traveltimes and first-order spreading of reflected/transmitted P waves
Cerveny, Vlastislav
22, Charles University, Faculty of Mathematics and Physics, Department of Geophysics, Praha 2012, pp-order traveltime. Symbol G denotes the first-order P-wave (greatest) eigenvalue of the generalized Christoffel-order slowness vector p0 at the source. Symbol c0 denotes the first-order approximation of P-wave phase velocity
SECOND{ORDER AND HIGHER{ORDER PERTURBATIONS OF TRAVEL TIME IN ISOTROPIC AND ANISOTROPIC MEDIA
Cerveny, Vlastislav
SECOND{ORDER AND HIGHER{ORDER PERTURBATIONS OF TRAVEL TIME IN ISOTROPIC AND ANISOTROPIC MEDIA Lud derivatives of travel time with respect to model parameters are re- ferred to as perturbations. Explicit equations for the second{order and higher{order perturbations of travel time in both isotropic
Enhancement of Nematic Order and Global Phase Diagram of a Lattice Model for Coupled Nematic Systems
NASA Astrophysics Data System (ADS)
Liarte, Danilo Barbosa; Salinas, Silvio Roberto
2012-08-01
We use an infinite-range Maier-Saupe model, with two sets of local quadrupolar variables and restricted orientations, to investigate the global phase diagram of a coupled system of two nematic subsystems. The free energy and the equations of state are exactly calculated by standard techniques of statistical mechanics. The nematic-isotropic transition temperature of system A increases with both the interaction energy among mesogens of system B, and the two-subsystem coupling J. This enhancement of the nematic phase is manifested in a global phase diagram in terms of the interaction parameters and the temperature T. We make some comments on the connections of these results with experimental findings for a system of diluted ferroelectric nanoparticles embedded in a nematic liquid-crystalline environment.
CHLOROPLAST GENE ORDER AND THE DIVERGENCE
Bryant, David
CHLOROPLAST GENE ORDER AND THE DIVERGENCE OF PLANTS AND ALGAE, FROM THE NORMALIZED NUMBER chloroplast genomes with known gene orders, with a focus on recently se- quenced members of the algal class and diversification of plants and algae, and their relationships with other chloroplast-containing organisms, are some
Science Orders Systems and Operations Manual.
ERIC Educational Resources Information Center
Kriz, Harry M.
This manual describes the implementation and operation of SCIENCE ORDERS, an online orders management system used by the Science and Technology Department of Newman Library at Virginia Polytechnic Institute and State University. Operational since January 1985, the system is implemented using the SPIRES database management system and is used to (1)…
Some Higher-Order Differential Equations
PRETEX (Halifax NS) #1 1054 1999 Mar 05 10:59:16
2010-01-20
Feb 16, 2007 ... Case 1: Second-Order Equations with the Dependent Variable Missing. If y does not ... Equation (1.11.9) is a first-order linear differential equation with standard form dv dx. ? x. ?1 .... (1.11.23) where ? is a positive constant. .... This chapter has provided an introduction to the theory of differential equations. A.
School Bullying and Social and Moral Orders
ERIC Educational Resources Information Center
Horton, Paul
2011-01-01
This article provides a theoretical consideration of the ways in which school bullying relates to social and moral orders and the relations of power that are central to the upholding of such orders. Moving away from the focus on individual aggressive intentionality that has hitherto dominated school bullying research, the article argues that…
VLSI Structures for Weighted Order Statistics Filters
L. E. Lucke; K. K. Parhi
1993-01-01
One-dimensional weighted order statistic (WOS) filters are non-linear filters which choose an output bmed on its weighted rank within a onedimensional window of sample inputs. These filters are an extension of the class of rank order filters and a subset of the class of stack filters. While many filter structures have been developed for rank oirder and stack filtering, none
Variable Affix Order: Grammar and Learning
ERIC Educational Resources Information Center
Ryan, Kevin M.
2010-01-01
While affix ordering often reflects general syntactic or semantic principles, it can also be arbitrary or variable. This article develops a theory of morpheme ordering based on local morphotactic restrictions encoded as weighted bigram constraints. I examine the formal properties of morphotactic systems, including arbitrariness, nontransitivity,…
Review essay \\/ What kind of order?
Robert Jackall
2003-01-01
Bernard E. Harcourt, Illusion of Order: The False Promise of Broken Windows Policing Cambridge, MA: Harvard University Press, 2001, x + 294 pp.David Garland, The Culture of Control: Crime and Social Order in Contemporary Society Chicago: University of Chicago Press, 2001, xiii + 307 pp.Andrea McArdle and Tanya Erzen (eds.), Zero Tolerance: Quality of Life and the New Police Brutality
Using Reflection to Develop Higher Order Processes
ERIC Educational Resources Information Center
Lerch, Carol; Bilics, Andrea; Colley, Binta
2006-01-01
The main purpose of this study was to look at how we used specific writing assignments in our courses to encourage metacognitive reflection in order to increase the learning that takes place. The study also aimed to aid in the development of higher order processing skills through the development of student reflection. The students involved in the…
The Ordering Analytic Approach to Hierarchical Analysis.
ERIC Educational Resources Information Center
Bart, William M.
This state-of-the-art review describes the genesis, structure, methods, applications, limitations and goals of the ordering analytic approach to hierarchical analysis, with specific reference to its relevance and use in educational, psychology and behavioral sciences. Hierarchy is defined as an "ordering" of objects such that the relation defined…
A New Approach to an Old Order.
ERIC Educational Resources Information Center
Rambhia, Sanjay
2002-01-01
Explains the difficulties middle school students face in algebra regarding the order of operations. Describes a more visual approach to teaching the order of operations so that students can better solve complex problems and be better prepared for the rigors of algebra. (YDS)
HIGHER-ORDER REVERSE TOPOLOGY James Hunter
Miller, Joseph S.
HIGHER-ORDER REVERSE TOPOLOGY by James Hunter A dissertation submitted in partial fulfillment #12;c Copyright by James Hunter 2008 All Rights Reserved #12;i ACKNOWLEDGMENTS I would like to thank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 #12;HIGHER-ORDER REVERSE TOPOLOGY James Hunter Under the supervision of Professor Steffen Lempp
Reading Achievement, Birth Order and Family Size.
ERIC Educational Resources Information Center
Hatzitheologou, E.
1997-01-01
Examined the relationship between reading achievement and birth order in 503 Greek children. Found that birth order was not related to vocabulary knowledge or reading comprehension at second grade, but total reading achievement and reading comprehension were higher for first- and second-born sixth graders than for later-born sixth graders. (KB)
Birth Order, Family Size and Educational Attainment
ERIC Educational Resources Information Center
de Haan, Monique
2010-01-01
This paper investigates the effect of family size and birth order on educational attainment. An instrumental variables approach is used to identify the effect of family size. Instruments for the number of children are twins at last birth and the sex mix of the first two children. The effect of birth order is identified, by examining the relation…
Perception of Serial Order in Infants
ERIC Educational Resources Information Center
Lewkowicz, David J.
2004-01-01
Serial order is fundamental to perception, cognition and behavioral action. Three experiments investigated infants' perception, learning and discrimination of serial order. Four- and 8-month-old infants were habituated to three sequentially moving objects making visible and audible impacts and then were tested on separate test trials for their…
Low-order Hamiltonian operators having momentum
Jirina Vodova
2012-12-17
We describe all fifth-order Hamiltonian operators in one dependent and one independent variable that possess the momentum, i.e., for which there exists a Hamiltonian associated with translation in the independent variable. Similar results for first- and third-order Hamiltonian operators were obtained earlier by Mokhov.