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1

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

SciTech Connect

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

Beek, D. van der; Petukhov, A.V.; Vroege, G.J.; Lekkerkerker, H.N.W. [Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands); Davidson, P.; Ferre, J.; Jamet, J.P. [Laboratoire de Physique des Solides, UMR 8502 CNRS, Universite Paris-Sud, Batiment 510, 91405 Orsay (France); Wensink, H.H. [Institut fuer Theoretische Physik II, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstrasse 1, Gebaeude 25.32, 40225 Duesseldorf (Germany); Bras, W. [Netherlands Organisation for Scientific Research (NWO), DUBBLE CRG, European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex (France)

2006-04-15

2

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

NASA Astrophysics Data System (ADS)

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.

Mark, J. Abraham Hudson; Peter, A. John

2014-04-01

3

Magnetic-field-induced phase transition in BiFeO3 observed by high-field electron spin resonance: Cycloidal to homogeneous spin order  

Microsoft Academic Search

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

Benjamin Ruette; S. Zvyagin; A. P. Pyatakov; A. Bush; J. F. Li; V. I. Belotelov; A. K. Zvezdin; D. Viehland

2004-01-01

4

Magnetic-field-induced charge order in the filled skutterudite SmRu4P12: Evidence from resonant and nonresonant x-ray diffraction  

NASA Astrophysics Data System (ADS)

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.

Matsumura, Takeshi; Michimura, Shinji; Inami, Toshiya; Hayashi, Yuya; Fushiya, Kengo; Matsuda, Tatsuma D.; Higashinaka, Ryuji; Aoki, Yuji; Sugawara, Hitoshi

2014-04-01

5

Magnetic-Field-Induced Electric Polarization in Multiferroic Nanostructures  

Microsoft Academic Search

Magnetic-field-induced electric polarization in nanostructured multiferroic composite films was studied by using the Green's function approach. The calculations showed that large magnetic-field-induced polarization could be produced in multiferroic nanostructures due to enhanced elastic coupling interaction. Especially, the 1-3 type films with ferromagnetic nanopillars embedded in a ferroelectric matrix exhibited large magnetic-field-induced polarization responses, while the 2-2 type films with ferroelectric

Ce-Wen Nan; Gang Liu; Yuanhua Lin; Haydn Chen

2005-01-01

6

Second-order quadrupolar and low-dimensionality effects upon NMR resonance spectra  

NASA Astrophysics Data System (ADS)

This paper deals with some formal problems which have been encountered in the study of ion dynamics in solid electrolytes with NMR. A time-dependent theory for second-order quadrupolar effects is presented which demonstrates that second-order contributions to the first moment of a line can give the same dynamical information on atomic motion as the spin-lattice relaxation rates. The effect of reduced dimensionality upon motional correlation functions is discussed. The results for two-dimensional and three-dimensional correlation functions, as calculated in the continuum diffusion limit, show that a simple relationship exists between the temperature and frequency dependence of the NMR parameters. Phenomenological rules are proposed to extract from the data an activation energy for the motion described by the correlation functions. A companion paper applies the theory to the 23Na and 27Al resonance in Na ?-alumina, for which Na ion transport occurs in a plane.

Bjorkstam, John L.; Villa, Marco

1980-12-01

7

Magnetic field induced transition in vanadium spinels.  

PubMed

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

Mun, E D; Chern, Gia-Wei; Pardo, V; Rivadulla, F; Sinclair, R; Zhou, H D; Zapf, V S; Batista, C D

2014-01-10

8

Superconductivity and magnetic-field-induced spin-density waves  

SciTech Connect

A recent theory of the magnetic-field-induced spin-density wave (FISDW) transitions observed in the Bechgaard Salts (TMTSF){sub 2}{ital X} emphasizes the role of the superconducting pairing interaction in FISDW formation. No superconductivity is observed in (TMTSF){sub 2}NO{sub 3}, unlike other metallic Bechgaard salts. Our study of (TMTSF){sub 2}NO{sub 3} in pressure up to 13 kbar, temperature down to 0.5 K, and magnetic field up to 30 T shows no sign of FISDW. The rapid'' magnetoresistance oscillations observed but unexplained in other Bechgaard salts are also observed here.

Kang, W.; Hannahs, S.T.; Chiang, L.Y.; Upasani, R.; Chaikin, P.M. (Department of Physics, Princeton University, Princeton, New Jersey 08544, (USA) Francis Bitter National Magnet Laboratory, Cambridge, MA 02139 Exxon Research and Engineering Company, Annandale, NJ 08801)

1990-11-26

9

Nematic, Smectic-A, and Smectic-C ordering in a system of parallel cylinders with quadrupolar interaction  

Microsoft Academic Search

We have studied the thermodynamics of a fluid of parallel cylinders which interact both through volume exclusion and through a longer-range quadrupolar interaction between point quadrupoles placed at the centres of the cylinders. The volume exclusion is treated using the Onsager approximation, and the long-range part of the potential is treated in mean field theory. At sufficiently high densities there

A. Poniewierski; T. J. Sluckin

1991-01-01

10

Powder MAS NMR lineshapes of quadrupolar nuclei in the presence of second-order quadrupole interaction.  

PubMed

We derive a complete analytical solution for the powder magic angle spinning (MAS) nuclear magnetic resonance (NMR) lineshape in the presence of second-order quadrupole interaction, considering a radiofrequency (rf) pulse of finite width, a finite MAS frequency, and a non-zero asymmetry parameter. (Ix) is calculated using two approaches. The first applies time-dependent perturbation theory in the presence of the rf pulse and stationary perturbation theory (SPT) in its absence. The second is based on the Magnus expansion of the density matrix in the interaction representation during the pulse and SPT in its absence. We solve the problem in the laboratory frame using the properties of the Fourier transform and spin operators. Diagonalisation is not required. Both approaches agree well with each other under all conditions and also with the transition probability approach for the central transition. The Magnus expansion exists at all times and the effect of the non-secular terms is negligible. We describe an analytical method of averaging (Ix) over the Euler angles and simulate the 11B MAS NMR lineshapes for crystalline and vitreous B2O3. A critical analysis is given of all earlier calculations of the MAS NMR lineshape. PMID:10928635

Ajoy, G; Ramakrishna, J; Bahçeli, S; Klinowski, J

2000-07-01

11

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

PubMed

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

Przybyli?ska, H; Springholz, G; Lechner, R T; Hassan, M; Wegscheider, M; Jantsch, W; Bauer, G

2014-01-31

12

Temperature and magnetic field induced multiple magnetic transitions in DyAg(2).  

PubMed

The magnetic properties of the rare-earth intermetallic compound DyAg(2) are studied in detail with the help of magnetization and heat capacity measurements. It is shown that the multiple magnetic phase transitions can be induced in DyAg(2) both by temperature and magnetic field. The detailed magnetic phase diagram of DyAg(2) is determined experimentally. It was already known that DyAg(2) undergoes an incommensurate to commensurate antiferromagnetic phase transition close to 10 K. The present experimental results highlight the first order nature of this phase transition, and show that this transition can be induced by magnetic field as well. It is further shown that another isothermal magnetic field induced transition or metamagnetic transition exhibited by DyAg(2) at still lower temperatures is also of first order nature. The multiple magnetic phase transitions in DyAg(2) give rise to large peaks in the temperature dependence of the heat capacity below 17 K, which indicates its potential as a magnetic regenerator material for cryocooler related applications. In addition it is found that because of the presence of the temperature and field induced magnetic phase transitions, and because of short range magnetic correlations deep inside the paramagnetic regime, DyAg(2) exhibits a fairly large magnetocaloric effect over a wide temperature window, e.g., between 10 and 60 K. PMID:21406918

Arora, Parul; Chattopadhyay, M K; Sharath Chandra, L S; Sharma, V K; Roy, S B

2011-02-01

13

Magnetic-field-induced twin boundary motion in magnetic shape-memory alloys  

NASA Astrophysics Data System (ADS)

This paper reports direct microscopic evidence of magnetoelastic coupling between ferroelastic twin domains and ferromagnetic Weiss domains in magnetic shape memory alloys, using the Ni-Mn-Ga Heusler alloys. In a martensitically transformed Ni2+xMn1-xGa single crystal, the magnetic domains were found to be superimposed upon the martensite twin domains. Simultaneous observation of magnetic domains and twin domains as a function of applied magnetic field shows that concomitant with the reconfiguration of magnetic domains in an applied magnetic field, ferroelastic twin domains also readjust their relative volume fraction in order to accommodate to the externally applied magnetic field. This readjustment is shown to occur by the displacement of twin domain walls. As a result, the volume fraction of one set of favorably oriented twin domains (with respect to magnetoelastic energy) increase at the expense of another set of unfavorably oriented twin domains. These studies would enable subsequent quantitative correlation between the magnetic-field-induced macroscopic strain and the microscopic self-adjustment of twin domains.

Chopra, Harsh Deep; Ji, Chunhai; Kokorin, V. V.

2000-06-01

14

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

SciTech Connect

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

Singleton, John [Los Alamos National Laboratory; Yaguchi, Hiroshi [TOKYO UNIV

2008-01-01

15

Modeling of the Stress and Magnetic Field-Induced Variant Reorientation in MSMAs  

Microsoft Academic Search

This paper is concerned with the modeling of the magnetic shape memory alloy (MSMA) constitutive response caused by the reorientation of martensitic variants. Following a sum- mary of the constitutive model previously proposed by the authors, the nonlinear and hysteretic strain and magnetization response of MSMAs are investigated for two main loading cases, namely the magnetic field-induced reorientation of variants

Bjoern Kieferand; Dimitris C. Lagoudas

16

Field-Induced Quadrupolar Ordered Phase for H\\parallel< 111> in Heavy-Fermion Compound YbCo2Zn20  

NASA Astrophysics Data System (ADS)

Magnetic susceptibility, high-field magnetization up to 500 kOe, and specific heat in a wide temperature range from 0.06 to 300 K were measured for single crystals of the cubic heavy-fermion compound YbCo2Zn20 in order to elucidate the electronic states of the compound at low temperatures. A strong increase in the magnetic specific heat in the form of Cmag/T below ˜1 K is approximately explained by the resonant level model for S = 1/2 with the Kondo temperature TK = 1 K, and an extremely large Cmag/T? 8 J/(K2\\cdotmol) below about 0.2 K is explained by considering the magnetic entropy of the doublet ground state in the 4f crystalline electric field (CEF) scheme of an Yb3+ ion, which corresponds to an extremely large electronic specific heat coefficient. The field-induced ordered phase for H\\parallel< 111>, which has recently been found by low-temperature magnetization measurements, was precisely studied by electrical resistivity and specific heat measurements, and was observed in a limited angular range around the < 111> direction. On the basis of CEF analyses, the level crossing of the two lowest CEF states is essentially important to understand the field-induced ordered phase, which can be reduced to a field-induced antiferro-quadrupolar ordering based on the ?3-type quadrupole moment O20.

Takeuchi, Tetsuya; Yoshiuchi, Shingo; Ohya, Masahiro; Taga, Yuki; Hirose, Yusuke; Sugiyama, Kiyohiro; Honda, Fuminori; Hagiwara, Masayuki; Kindo, Koichi; Settai, Rikio; ?nuki, Yoshichika

2011-11-01

17

Magnetic-field-induced phases in anisotropic triangular antiferromagnets: Application to CuCrO2  

NASA Astrophysics Data System (ADS)

We introduce a minimal spin model for describing the magnetic properties of CuCrO2. Our Monte Carlo simulations of this model reveal a rich magnetic-field-induced phase diagram, which explains the measured field dependence of the electric polarization. The sequence of phase transitions between different multiferroic states arises from a subtle interplay between spatial and spin anisotropy, magnetic frustration, and thermal fluctuations. Our calculations are compared to new measurements up to 92 T.

Lin, Shi-Zeng; Barros, Kipton; Mun, Eundeok; Kim, Jae-Wook; Frontzek, Matthias; Barilo, S.; Shiryaev, S. V.; Zapf, Vivien S.; Batista, Cristian D.

2014-06-01

18

Magnetic-field-induced charge current in quantum wells with spin orbit coupling  

Microsoft Academic Search

We calculated the charge current response in a two-dimensional electron gas in the presence of Rashba spin-orbit coupling and electron-impurity scattering, under an in-plane time-dependent applied magnetic field. Our formalism rests on the density matrix method and quantum transport equation. It was shown that there exists a magnetic-field-induced charge transport due to the photon-excited electrons scattered by impurities in the

Pin Lyu; Chao Zhang

2007-01-01

19

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

SciTech Connect

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

Louie, S.G.; Zhu, X.

1992-08-01

20

Theory of magnetic field-induced charge-density-wave phases  

Microsoft Academic Search

We elaborate an analytical theory of a cascade of magnetic field-induced charge-density-wave (FICDW) phases. It is shown that\\u000a the following features distinguish it from the well-known spin-density-wave cascade: (1) the FICDW phases exist at temperatures\\u000a much lower than the characteristic CDW transition temperature at H=0; (2) the cascade of the FICDW phases dramatically changes at certain directions of a magnetic

A. G. Lebed

2003-01-01

21

Magnetic field induced ferroelectric loop in Bi0.75Sr0.25FeO3-delta  

Microsoft Academic Search

Magnetic field induced ferroelectric hysteresis loop observed in Bi0.75Sr0.25FeO3-delta is of prime importance. The coexistence of antiferromagnetism and weak ferromagnetism is responsible for the original magnetoelastic and magnetoferroelectric properties. Upon external magnetic field application, the existence of a magnetostrictive effect supports a structural transition toward a homogeneous antiferromagnetic and ferroelectric phase. The magnetic field induced polarization is among the highest

Bohdan Kundys; Antoine Maignan; Christine Martin; Ninh Nguyen; Charles Simon

2008-01-01

22

Magnetic field-induced reverse martensitic transformation in NiMnGaCu alloy  

NASA Astrophysics Data System (ADS)

The reverse martensitic transformation was monitored by testing the x-ray diffraction patterns with increasing temperatures in an Ni46Mn33Ga17Cu4 alloy. A large magnetization change from a weak-magnetic martensite phase to a ferromagnetic austenite phase has been found on the M-T curves of heating cycle in this alloy. The reverse martensitic transformation temperatures have been lowered by 7 K under the magnetic field of 90 kOe. The magnetic field-induced reverse martensitic transformation has been confirmed at a fixed temperature in this alloy, demonstrating that another alloy performing the MFIRMT is discovered: NiMnGaCu alloy.

Li, Panpan; Wang, Jingmin; Jiang, Chengbao; Xu, Huibin

2011-07-01

23

High magnetic field induced charge density waves and sign reversal of the Hall coefficient in graphite.  

PubMed

We report on the investigation of magnetic field induced charge density waves and Hall coefficient sign reversal in a quasi-two-dimensional electronic system of highly oriented pyrolytic graphite under very strong magnetic field. The change of Hall sign coefficient from negative to positive occurs at low temperature and high magnetic field just after the charge density wave transition, suggesting the role of hole-like quasi-particles in this effect. Angular dependent measurements show that the charge density wave transition and Hall sign reversal fields follow the magnetic field component along the c-axis of graphite. PMID:21403339

Kumar, Amit; Poumirol, Jean-Marie; Escoffier, Walter; Goiran, Michel; Raquet, Bertrand; Claude Pivin, Jean

2010-11-01

24

Magnetic field induced insulating state in bilayer graphene at charge neutral point  

NASA Astrophysics Data System (ADS)

We investigate magnetotransport in the vicinity of the charge neutral point (CNP) in bilayer graphene at low temperatures. The CNP is found to vary with applied magnetic fields. Through measuring the transfer curves under different magnetic fields and at different temperatures, the temperature dependence of the peak resistivity at the CNP and under a fixed magnetic field is extracted. At low temperatures, it is found that the peak resistivity at the CNP increases exponentially with decreasing temperature under 14 T, which indicates the gap opening in zero-energy Landau level. The origins of such magnetic field induced insulating behavior are discussed.

Zhou, Yang-Bo; Zhang, Liang; Yu, Da-Peng; Liao, Zhi-Min

2014-04-01

25

Far infrared study of magnetic field induced normal states of La1.94Sr0.06CuO4  

NASA Astrophysics Data System (ADS)

We report on the ab-plane optical properties of the magnetic field induced normal state of La1.94Sr0.06CuO4 (Tc=5.5 K), the first such study. We apply strong magnetic fields (4 T and 16 T) along the c-axis . We find that at 4 T fields, which are strong enough to destroy superconductivity, the normal state at 1.4 K is very similar to the normal state at 20 K in zero field. However at higher fields we observed a gap-like depression in the optical conductivity at low frequency along with parallel growth of a broad absorption peak centered at higher frequency. The spectral weight loss in the depression at low frequency is recovered by the spectral weight in the broad peak. We attribute the magnetic field induced gap-like depression and the broad peak to a competing charge order to superconducting order or charge localization in ab-plane of the system.

Timusk, Thomas; Rõõm, Toomas; Nagel, Urmas; Hüvonen, Daniel; Hawthorn, David; Wakimoto, S.; Zhang, H.; Hwang, Jungseek

2012-02-01

26

Dynamic-angle spinning and double rotation of quadrupolar nuclei  

SciTech Connect

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

Mueller, K.T. (Lawrence Berkeley Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Chemistry)

1991-07-01

27

Magnetic-field-induced transformation in FeMnGa alloys  

SciTech Connect

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.

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

28

Magnetic-field-induced optical anisotropy in ferrofluids: a time-dependent light-scattering investigation.  

PubMed

We report an experimental investigation of time dependent anisotropic light scattering by an aqueous suspension of tetramethyl ammonium hydroxide coated Fe3O4 nanoparticles (approximately 6 nm) under the ON-OFF transient of an external dc magnetic field. The study employs the synchronized recording and measurement of the two magnetic-field-induced light-scattering patterns produced by two identical orthogonal He-Ne laser beams passing through the ferrofluid sample and propagating parallel and perpendicular to the applied field, respectively. From these patterns, we extract the time dependence of the induced optical anisotropy, which provides a measure of the characteristic time scale and kinematic response for field-induced structure formation in the sample. We propose that the time evolution of the scattering patterns, which is very fast at short times and significantly slower at long times, can be explained using a model based on a two-stage chain formation and coarsening processes. PMID:19113131

Rablau, Corneliu; Vaishnava, Prem; Sudakar, Chandran; Tackett, Ronald; Lawes, Gavin; Naik, Ratna

2008-11-01

29

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

PubMed

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

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

2014-07-10

30

Magnetic-field-induced multiple electronic states in La{sub 0.5}Ca{sub 0.5}MnO{sub 3+{delta}}  

SciTech Connect

We have observed multiple electronic states in the presence of a magnetic field in the half-doped La{sub 0.5}Ca{sub 0.5}MnO{sub 3+{delta}} system. The resistivity of each state differs from one another by at least one order of magnitude. Application of a magnetic field induces first-order phase transitions among these states. A maximum 10{sup 9}-fold magnetoresistance ratio has been observed at 4.2 K between the least and the most conductive phases. Our results differ from early observations that there is only one metal-to-insulator (two states) transition in other related half-doped systems. {copyright} {ital 1996 The American Physical Society.}

Xiao, G. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)] [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); McNiff, E.J. Jr. [Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Gong, G.Q. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)] [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Gupta, A. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)] [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Canedy, C.L. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)] [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Sun, J.Z. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)] [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

1996-09-01

31

Phenomenology of giant magnetic-field-induced strain in ferromagnetic shape-memory materials (invited)  

SciTech Connect

Ferromagnetic shape-memory alloys have recently emerged as a new class of active materials showing very large magnetic-field-induced extensional strains. Recently, a single crystal of a tetragonally distorted Heusler alloy in the NiMnGa system has shown a 5% shear strain at room temperature in a field of 4 kOe. The magnetic and crystallographic aspects of the twin-boundary motion responsible for this effect are described. Ferromagnetic shape-memory alloys strain by virtue of the motion of the boundaries separating adjacent twin variants. The twin-boundary motion is driven by the Zeeman energy difference between the adjacent twins due to their nearly orthogonal magnetic easy axes and large magnetocrystalline anisotropy. The twin boundary constitutes a nearly 90 degree sign domain wall. Essentially, twin-boundary motion shorts out the more difficult magnetization rotation process. The field and stress dependence of the strain are reasonably well accounted for by minimization of a simple free energy expression including Zeeman energy, magnetic anisotropy energy, internal elastic energy, and external stress. Models indicate the limits to the magnitude of the field-induced strain and point to the material parameters that make the effect possible. The field-induced strain in ferromagnetic shape-memory alloys is contrasted with the more familiar phenomenon of magnetostriction. (c) 2000 American Institute of Physics.

O'Handley, R. C. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Murray, S. J. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Marioni, M. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Nembach, H. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Allen, S. M. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2000-05-01

32

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

PubMed

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

Tschulik, Kristina; Compton, Richard G

2014-07-21

33

Magnetic field induced transition rates in Ne- and Be-like ions for plasma diagnostics and E1M1 two-photon decay rate determination  

NASA Astrophysics Data System (ADS)

We report on theoretical results of magnetic field induced transitions (MITs) in Ne- and Be-like ions without nuclear spin for two applications. Firstly, MITs are promising candidates in the determination of magnetic fields in plasmas. In our work on Ne-like ions we present accurate theoretical MIT rates for 2p6 1So – 2p53s 3Po,2 [1]. Furthermore, for Be-like ions, it has been proposed to extract the rate of the E1M1 two-photon transition 2s2 1S0 – 2s2p 3P0 by measuring the lifetime of the 3P0 state using a storage ring, which involves an external magnetic field. The MIT rates are carefully evaluated and shown to be of the same order as the E1M1 rates [2].

Grumer, Jon; Li, Jiguang; Li, Wenxian; Andersson, Martin; Brage, Tomas; Hutton, Roger; Jönsson, Per; Yang, Yang; Zou, Yarning

2014-04-01

34

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

PubMed

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

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

2013-06-18

35

Magnetic field induced ferroelectric loop in Bi0.75Sr0.25FeO3-?  

NASA Astrophysics Data System (ADS)

Magnetic field induced ferroelectric hysteresis loop observed in Bi0.75Sr0.25FeO3-? is of prime importance. The coexistence of antiferromagnetism and weak ferromagnetism is responsible for the original magnetoelastic and magnetoferroelectric properties. Upon external magnetic field application, the existence of a magnetostrictive effect supports a structural transition toward a homogeneous antiferromagnetic and ferroelectric phase. The magnetic field induced polarization is among the highest reported for BiFeO3 based systems in either thin film or bulk form (Pr=96 ?C/cm2 at 10 T) while the ferroelectric coercive field is among the lowest reported (Hc=661 V/cm at 10 T). These properties make this material very attractive for technical applications.

Kundys, Bohdan; Maignan, Antoine; Martin, Christine; Nguyen, Ninh; Simon, Charles

2008-03-01

36

Novel electrochemical sensing platform based on magnetic field-induced self-assembly of Fe3O4@Polyaniline nanoparticles for clinical detection of creatinine.  

PubMed

A novel electrochemical sensing platform based on magnetic field-induced self-assembly of Fe3O4@Polyaniline nanoparticles (Fe3O4@PANI NPs) has been for the first time fabricated for the sensitive detection of creatinine in biological fluids. The template molecule, creatinine, was self-assembled on the surface of Fe3O4@PANI NPs together with the functional monomer aniline by the formation of N-H hydrogen bonds. After pre-assembled, through the magnetic-induction of the magnetic glassy carbon electrode (MGCE), the ordered structure of molecularly imprinted polymers (MIPs) were established by the electropolymerization and assembled on the surface of MGCE with the help of magnetic fields by a simple one-step approach. The structural controllability of the MIPs film established by magnetic field-induced self-assembly was further studied. The stable and hydrophilic Fe3O4@PANI can not only provide available functionalized sites with which the template molecule creatinine can form hydrogen bond by the abundant amino groups in PANI matrix, but also afford a promoting pathway for electron transfer. The as-prepared molecularly imprinted electrochemical sensor (MIES) shows good stability and reproducibility for the determination of creatinine with the detection limit reached 0.35 nmol L(-1) (S/N=3). In addition, the highly sensitive and selective MIES has been successfully used for the clinical determination of creatinine in human plasma and urine samples. The average recoveries were 90.8-104.9% with RSD lower than 2.7%. PMID:24487254

Wen, Tingting; Zhu, Wanying; Xue, Cheng; Wu, Jinhua; Han, Qing; Wang, Xi; Zhou, Xuemin; Jiang, Huijun

2014-06-15

37

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

NASA Astrophysics Data System (ADS)

High magnetic fields are used to kill superconductivity and probe what happens to system when it cannot reach the ideal ground state, i.e. what is the normal-state ground state? Early work in High-Tc, where the application of magnetic field destroyed the zero resistance state and recovered a resistivity value that connected continuously with the zero field curve, lead people to believe this magnetic-field-induced-state had fully driven the system normal, revealing the true underlying ground state, without any vestige of superconductivity. Many experiments done in this region of phase space have results interpreted as coming from the low energy ground state excitations. With the emergence of ultra-clean crystals in a unique family of hole doped high-Tc superconductors, YBa2Cu3O 7-delta, YBCO, a new and highly unexpected phenomena of quantum oscillations were discovered, and they followed the standard Liftshitz-Kosevich (LK) theory for a normal metal. The results suddenly made the problem of high-T c appear to be analogous to superconductivity in the organics, which is brought about by a wave-vector nesting and Fermi surface reconstruction. The only problem, it appeared, that needed to be reconciled was with Angle Resolved Photo-Emission Spectroscopy (ARPES) and Scanning Tunneling Microscopy (STM) data that claimed to see no such Fermi surface, instead only "arcs", a set of disconnected segments in the Brillouin zone which quasiparticle peaks are observed at the Fermi energy, which in a mean field description does not allow for a continuous Fermi surface contour. These two discrepancies led to the "arc vs pocket" debate, which is still unresolved. The other kink in the quantum oscillation armor is that, to this date, quantum oscillations in the hole-doped cuprates have only been seen in YBCO, the only cuprate structure to have CuO chains, which conduct and are located in between two CuO2 superconducting planes in the unit cell. In an attempt to reconcile the "arc vs pocket" debate we measure specific heat on an ultra-clean de-twinned single crystal of underdoped YBCO 6.56 with a Tc = 60 K, up to fields twice irreversibility field, define as the onset of the resistive transition. The zero temperature extrapolation of the electronic contribution to the specific heat, gamma, is the total quasiparticle density of states. For a two-dimensional system with parabolic energy bands, gamma is simply the sum of each pocket multiplied by its effective mass. Therefore, by determining gamma at high fields and using previously determined values for the effective mass from quantum oscillation transport measurements we can simply play a counting game to determine the number of pockets in the Fermi surface. Furthermore, at low fields the response to the specific heat as a function of magnetic field in a d-wave superconductor is known to have a (H) dependence, and we can look for deviations from this (H) , which are expected to happen when the system is no longer in a superconducting state. Results from our specific heat experiment shed new light on the true nature of the magnetic field induced "normal" state, and should force reinterpretation of many experimental findings. The specific heat measurements foremost show a smooth evolution of gamma from low to high magnetic fields which follows a Ac (H) dependence, with the prefactor, Ac giving the correct magnitude for the anisotropy of the d-wave superconducting gap. This means with the application of magnetic fields strong enough to restore the resistive state, the superconducting gap still exits. Additionally, we see quantum oscillations that follow conventional LK formalism and can determine an effective mass uniquely, where no fitting parameters are required. Interestingly, these oscillations fit on top of the (H) finding. How can the (H) and quantum oscillation whose phenomena arise from very different physics be reconciled? Looking at our own zero field gamma value of 1.85 mJ mol-1 K-2, which is intrinsic for YBCO, allows the pocket counting game

Riggs, Scott Chandler

38

Solid-liquid equilibrium for quadrupolar molecules  

Microsoft Academic Search

Theoretical calculations are presented of solid-liquid equilibrium for linear quadrupolar molecules, focusing especially on the ratio of the triple point temperature to the critical temperature. The proposed treatment uses the hard quadrupolar dumbbell model as the reference system, and incorporates the effect of dispersion forces through a mean-field term. The reference system of quadrupolar hard dumbbells is described using perturbation

C. Vega; P. A. Monson

1995-01-01

39

Magnetic-field-induced spin flop transition and magnetoelectric effect in Ca2Fe2-xAlxO5  

NASA Astrophysics Data System (ADS)

Magnetic-field-induced spin flop transition and magnetoelectric effect in noncentrosymmetric Ca2Fe2-xAlxO5 (0.5 ? x ? 1) single crystals have been investigated. Temperature dependence of magnetic susceptibility shows that the compounds have antiferromagnetic transition temperatures TN above room temperature. The spin easy axis varies from the c axis to the a axis with increasing Al content x. When a magnetic field is applied along the spin easy axis, a spin flop transition takes place, accompanied by anomalies in the electric polarization and dielectric constant. The anomalies can be ascribed to a noncollinear spin arrangement in the domain walls between two magnetic phases and/or the spin direction dependent modulation of the metal-ligand hybridization. Such a polarization change with a spin flop transition in polar antiferromagnets may provide a route to realize large magnetoelectric coupling at high temperatures.

Abe, N.; Khanh, N. D.; Sasaki, T.; Arima, T.

2014-02-01

40

Magnetic-field-induced quantum criticality in a spin- S planar ferromagnet with single-ion anisotropy  

NASA Astrophysics Data System (ADS)

The effects of single-ion anisotropy on quantum criticality in a d-dimensional spin- S planar ferromagnet is explored by means of the two-time Green's function method. We work at the Tyablikov decoupling level for exchange interactions and the Anderson-Callen decoupling level for single-ion anisotropy. In our analysis a longitudinal external magnetic field is used as the non-thermal control parameter and the phase diagram and the quantum critical properties are established for suitable values of the single-ion anisotropy parameter D. We find that the single-ion anisotropy has sensible effects on the structure of the phase diagram close to the quantum critical point. However, for values of the uniaxial crystal-field parameter below a positive threshold, the conventional magnetic-field-induced quantum critical scenario remains unchanged.

Mercaldo, M. T.; Rabuffo, I.; De Cesare, L.; Caramico D'Auria, A.

2013-08-01

41

Disorder and magnetic-field-induced breakdown of helical edge conduction in an inverted electron-hole bilayer  

NASA Astrophysics Data System (ADS)

We calculate the conductance of a two-dimensional bilayer with inverted electron-hole bands to study the sensitivity of the quantum spin Hall insulator (with helical edge conduction) to the combination of electrostatic disorder and a perpendicular magnetic field. The characteristic breakdown field for helical edge conduction splits into two fields with increasing disorder, a field Bc for the transition into a quantum Hall insulator (supporting chiral edge conduction) and a smaller field Bc' for the transition to bulk conduction in a quasimetallic regime. The spatial separation of the inverted bands, typical for broken-gap InAs/GaSb quantum wells, is essential for the magnetic-field-induced bulk conduction—there is no such regime in HgTe quantum wells.

Pikulin, D. I.; Hyart, T.; Mi, Shuo; Tworzyd?o, J.; Wimmer, M.; Beenakker, C. W. J.

2014-04-01

42

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

43

Magnetic-field-induced odd-frequency superconductivity in s-wave superconductors  

NASA Astrophysics Data System (ADS)

The wavefunction of the Cooper pair of the conventional BCS state is characterized by an evenparity (s-wave) spin-singlet state. An external magnetic field is well known to modify the wavefunction of the Cooper pair and to break the conventional BCS superconducting state. We find that the wavefunction of the modified Cooper pair contains a spin-triplet component with s-wave orbital symmetry. While the spin-triplet s-wave Cooper pair is forbidden owing to the fermion property, it is permitted in the generalized theoretical framework containing an odd-frequency dependence of the order parameter. We investigate this point on the basis of the self-consistent calculation in the Eliashberg theory and find that the odd-frequency order parameter coexists with the evenfrequency one. We also report how the physical properties are affected by the induced odd-frequency superconducting order parameter.

Matsumoto, Masashige; Koga, Mikito; Kusunose, Hiroaki

2013-08-01

44

Magnetic-Field-induced Transitions in Multiferroic TbMnO3 Probed by Resonant  

SciTech Connect

Multiferroic TbMnO3 is investigated using x-ray diffraction in high magnetic fields. Measurements on first and second harmonic structural reflections due to modulations induced by the Mn and Tb magnetic order are presented as function of temperature and field oriented along the a and b-directions of the crystal. The relation to changes in ordering of the rare earth moments in applied field is discussed. Observations below T{sub N}(Tb) without and with applied magnetic field point to a strong interaction of the rare earth order, the Mn moments and the lattice. Also, the incommensurate to commensurate transition of the wave vector at the critical fields is discussed with respect to the Tb and Mn magnetic order and a phase diagram on basis of these observations for magnetic fields H||a and H||b is presented. The observations point to a complicated and delicate magneto-elastic interaction as function of temperature and field.

Strempfer,J.; Bohnenbuck, B.; Zegkinoglou, I.; Aliouane, N.; Landsgesell, S.; Zimmermann, M.; Argyriou, D.

2008-01-01

45

Angular dependence of magnetic-field-induced phase transitions in CeCoIn_5e  

NASA Astrophysics Data System (ADS)

We present the first calorimetric evidence for a magnetic-field-angle-dependent Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) superconducting state in the quasi 2-D heavy fermion superconductor CeCoIn5 at low temperatures. With Hallel[001], we confirm the presence of a single (first-order) phase transitionfootnote[1]A. Bianchi et al., PRL 89 (2002) 137002. from the superconducting to normal state. With H?[001], however, we observe two phase transitions: a first-order phase transition at Hc2 plus an additional (higher-order) phase transition within the superconducting state. As the field is rotated away from this orientation, H_c2 decreases in field but the threshold field for the second transition remains unchanged. Once H_c2 falls below this threshold field, however, the second transition is no longer observed. These results are in good agreement with recent theoretical predictionsfootnote[2]S. Matsuo et al., J. Phys. Soc. Jpn 67(1998)280; M. Houzet and A. Buzdin, PRB 63(2001)184521. for a second order phase transition between a uniform superconducting phase (U) and a spatially modulated FFLO superconducing phase with increasing magnetic field, followed by a first-order phase transition between the FFLO to normal metal phase (N) at still higher fields. The phase boundary for this new, lower field transition decreases with decreasing temperature, in disagreement with traditional models but in agreement with calculationsfootnote[3]H. Burkhardt and D. Rainer, Ann. der Physik 3(1994)181. that include the effect of the spin-dependent exchange interaction.

Fortune, Nathanael

2003-03-01

46

High Magnetic Field Induced Charge Density Wave State in a Quasi-One-Dimensional Organic Conductor  

Microsoft Academic Search

The quasi-one-dimensional organic conductor (Per)2Pt(mnt)2 exhibits a charge density wave ground state below 8 K. Magnetoresistance and magnetization measurements show that the charge density wave is suppressed with magnetic fields of order 20 T, above which a high resistance state, with a cascade of subphases, appears. This new state, tentatively identified as a field induced charge density wave, reenters a

D. Graf; E. S. Choi; J. S. Brooks; M. Matos; R. T. Henriques; M. Almeida

2004-01-01

47

Magnetic field induced properties of manganite perovskites with colossal magnetoresistance (invited)  

SciTech Connect

We present a systematic study of the magnetotransport and magnetic properties of the half-doped La{sub 0.5}Ca{sub 0.5}MnO{sub 3+{delta}} system. The solid is a metamagnet which undergoes a first-order antiferromagnet (AFM) to ferromagnet (FM) phase transition under a field or by changing temperature. Associated with the AFM{endash}FM transition is an insulator to metal transition. A maximum 10{sup 9}-fold magnetoresistance ratio has been observed at 4.2 K between the least and the most conductive states. At low T ({le}50 K), we have also observed two additional metastable electronic states in the canted AFM state at certain fields. The resistivity of each state differs from one another by at least one order of magnitude. The existence of these multiple states may be related to the unique charge- and spin-ordered state of the half-doped manganite. {copyright} {ital 1997 American Institute of Physics.}

Xiao, G.; Gong, G.Q.; Canedy, C.L. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)] [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); McNiff, E.J. , Jr. [Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Gupta, A. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)] [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

1997-04-01

48

Molecular Dynamics Simulation of Magnetic Field Induced Orientation of Nanotube-Polymer Composite  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations are carried out to study the reorientation of single wall carbon nanotubes in a polyethylene matrix under the influence of a 25 T magnetic field. The simulations are based on a variant of velocity Verlet algorithm, which relaxes the Larmor time-step restriction while preserving second-order accuracy. Simulations reveal that the unfolding and reorganization of the polyethylene (PE) chain facilitates the reorientation of the single wall carbon nanotubes closer to the direction of the applied magnetic field. Also, they bring out the difference between the behavior of the carbon nanotubes of zigzag chirality and that of armchair chirality.

Al-Haik, Marwan S.; Hussaini, M. Yousuff

2006-11-01

49

General relativistic simulations of magnetic field-induced explosions from stellar core collapse  

NASA Astrophysics Data System (ADS)

The explosion mechanism behind core-collapse supernovae remains an active area of research. In order to explore the role of magnetohydrodynamic (MHD) effects in the explosion, we perform axisymmetric simulations of magnetized, rotating cores collapsing to proto-neutron stars (PNSs) in full general relativity (dynamical spacetime). We confirm that significant differential rotation results even when the rotation of the progenitor is initially uniform. Consequently, the magnetic field is amplified both by magnetic winding and the magnetorotational instability (MRI). Following PNS formation, strong MHD outflows lead to losses of rest mass, energy, and angular momentum from the system which could play a role in rejuvenating a stalled supernova shock.

Liu, Yuk Tung; Shibata, Masaru; Shapiro, Stuart; Stephens, Branson

2007-04-01

50

Extremely low frequency magnetic fields induce oxidative stress in rat brain.  

PubMed

The present investigation was conducted to understand the influence of long-term exposure of rats to extremely low frequency magnetic fields (ELF-MF), focusing on oxidative stress (OS) on different regions of rat's brain. Male Wistar rats (21-day-old) were exposed to ELF-MF (50 Hz; 50 and 100 µT) for 90 days continuously; hippocampal, cerebellar and cortical regions from rats were analyzed for (i) reactive oxygen species (ROS), (ii) metabolites indicative of OS and (iii) antioxidant enzymes. In comparison to control group rats, the rats that were continuously exposed to ELF-MF caused OS and altered glutathione (GSH/GSSG) levels in dose-dependent manner in all the regions of the brain. Accumulation of ROS, lipid peroxidation end products and activity of superoxide dismutase in different regions was in the descending order of cerebellum < hippocampus < cortex. Decrement in GSH/GSSG levels and increment in glutathione peroxidase activity were in the descending order of hippocampus < cerebellum < cortex. The continuous exposure to ELF-MF caused OS in all the examined regions of brain more significantly at 100 µT than at 50 µT. Varied influences observed in different regions of the brain, as documented in this study, may contribute to altered metabolic patterns in its related regions of the central nervous system, leading to aberrant neuronal functions. PMID:24334533

Manikonda, Pavan K; Rajendra, Pilankatta; Devendranath, D; Gunasekaran, B; Channakeshava; Aradhya, Shivakumara R S; Sashidhar, Rao B; Subramanyam, Chivukula

2014-03-01

51

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

PubMed

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

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

2011-05-18

52

Neutron diffraction study of the magnetic-field-induced transition in Mn3GaC  

NASA Astrophysics Data System (ADS)

The antiperovskite Mn3GaC 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.

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

2014-01-01

53

Phase transitions in a ferrofluid at magnetic-field-induced microphase separation.  

PubMed

In the presence of a magnetic field applied perpendicular to a thin sample layer, a suspension of magnetic colloidal particles (ferrofluid) can form spatially modulated phases with a characteristic length determined by the competition between dipolar forces and short-range forces opposing density variations. We introduce models for thin-film ferrofluids in which magnetization and particle density are viewed as independent variables and in which the nonmagnetic properties of the colloidal particles are described either by a lattice-gas entropy or by the Carnahan-Starling free energy. Our description is particularly well suited to the low-particle-density regions studied in many experiments. Within mean-field theory, we find isotropic, hexagonal and stripe phases, separated in general by first-order phase boundaries. PMID:11690032

Lacoste, D; Lubensky, T C

2001-10-01

54

Asymmetry of the magnetic field-induced superconducting state B-T phase diagram induced by hydrostatic pressure  

NASA Astrophysics Data System (ADS)

We investigated, by electrical transport techniques, the effect of hydrostatic pressure on the recently discovered [1,2] magnetic field-induced superconducting state (FISC) of the ?-(BETS)_2FeCl4 compound. At zero field a small amount of hydrostatic pressure induced, for instance, by the solidification of the pressure medium, considerably ncreases the conductivity of the metallic state at low temperatures. Furthermore, it stabilizes superconductivity at TC ~= 5.5 K and suppresses the transition towards the insulating Néel state, from TN = 8.5 K at p = 1 bar, to TN ~= 3.5 K. The application of hydrostatic pressure does not seem to affect neither the transition temperature towards the FISC state nor the mechanism responsible for its suppression at very high fields. Nevertheless, it displaces the phase boundary between the metallic and FISC states towards much lower critical fields. This asymmetry, in the T-B phase diagram, is not easily conciliated with the original description of the FISC state in terms of the so-called Jaccarino-Peter compensation effect [2]. [1] S. Uji, et al., Nature 410, 908 (2001). [2] L. Balicas, J. S. Brooks, K. Storr, S. Uji, M. Tokumoto, H. Tanaka, H. Kobayashi, A. Kobayashi, V. Barzykin, and L. P. Gor'kov, Phys. Rev. Lett. 87, 067002 (2001).

Balicas, L.; Brooks, J. S.; Storr, K.; Uji, S.; Kobayashi, H.; Kobayashi, A.; Tokumoto, M.

2002-03-01

55

Magnetic-field-induced phase transitions in the quasi-one-dimensional organic conductor HMTSF-TCNQ  

NASA Astrophysics Data System (ADS)

Motivated by an interest to see if the field-induced (FI) phase in the charge-density wave (CDW) system is similar to the field-induced-SDW (FISDW) in (TMTSF)2X, (TMTSF: tetramethyltetraselenafulvalene), we examined the magnetic-field-induced phases in a quasi-one-dimensional (Q1D) organic conductor HMTSF-TCNQ (hexamethylene- tetraselenafulvalene- tetracyanoquinodimethane) under a pressure of 1.1 GPa, where the CDW occurring at 30 K is suppressed. The work was carried out by measurements of angular-dependent magnetoresistance oscillations and exploratory work on the Hall effect. It turned out that the FI-phase, most likely a FICDW for B > 0.1 T, accompany a quantum Hall effect, and the FI-phase transitions are controlled by the field component along the least conducting axis. Above 10 T, the lowest Landau level of the small 2D Fermi pocket (due to incomplete nesting of Fermi surface) exceeds the Fermi level, reaching the quantum limit. Although there are many differences between the CDW (HMTSF-TCNQ) and SDW ((TMTSF)2X) systems, a similar scenario for field-induced phases seems to hold.

Murata, K.; Fukumoto, Y.; Yokogawa, K.; Takaoka, R.; Kang, W.; Brooks, J. S.; Graf, D.; Yoshino, H.; Sasaki, T.; Kato, R.

2014-04-01

56

Magnetic Field Induced Phases of Ca2RuO4 and Ca3Ru2O7  

NASA Astrophysics Data System (ADS)

We present a Raman scattering study of the magnetic field induced phases in the layered ruthenates Ca2RuO4 and Ca3Ru2O7. Single-layer Ca2RuO4 has an antiferromagnetic ground state, is a paramagnetic (PM) insulator above TN = 113 K and is a PM metal above TMI = 357 K, while double-layer Ca3Ru2O7 has an antiferromagnetic insulating ground state, is metallic above TMI = 48 K, and is paramagnetic above TN = 56 K. Applied fields oriented in the a-b planes of both these materials produce dramatic changes to both the magnetic and vibrational spectra; these changes are associated with field-induced changes in the Ru orbital populations of these materials. In this talk, we compare the field induced orbital, magnetic, and conducting phases observed in Ca2RuO4 and Ca3Ru2O7. *Work supported by NSF DMR02-44502, NSF DMR02-40813, and DOE DEFG02-91ER45439.

Karpus, J. F.; Gupta, R.; Barath, H.; Cooper, S. L.; Cao, G.

2006-03-01

57

Magnetic field-induced currents in the human body in proximity of power lines  

SciTech Connect

Electric currents induced due to 60 Hz magnetic fields in a human body placed in a close proximity of various high voltage transmission lines are computed. A realistic model of the human body from the anatomical and electrical point of view with resolution of 1.3 cm for the body and 0.665 cm for the head is used. The computations are performed using the impedance method. Three representative configurations of high voltage transmission lines, namely 500 kV, 138 kV and 25 kV are analyzed. The results indicate that the maximum current densities of the order of 0.2 {micro}A/cm{sup 2} can be induced in a lineman working on a 500 kV line (0.5 m away from closest conductors). A good correlation can be seen between the computed magnetic field in the location of the human body and the induced current densities. The induced currents computed here and estimated from measured magnetic fields in various power line environments are compared to those for typical home and office exposures, including appliances.

Stuchly, M.A.; Zhao, S. [Univ. of Victoria, British Columbia (Canada). Dept. of Electrical and Computer Engineering] [Univ. of Victoria, British Columbia (Canada). Dept. of Electrical and Computer Engineering

1996-01-01

58

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

59

Isotropic chemical shifts and quadrupolar parameters of oxygen-17 using dynamic-angle spinning NMR  

SciTech Connect

Several oxygen-17-enriched silicates were studied using dynamic-angle spinning (DAS) NMR spectroscopy at two magnetic field strengths. The DAS method averages second-order quadrupolar interactions by reorienting a sample about a time-dependent axis, thereby yielding high-resolution spectra for half-odd integer spin quadrupolar nuclei such as oxygen-17. A narrow spectral line is observed for each distinct oxygen site in a powdered sample at the sum of the isotropic chemical shift and the field-dependent isotropic second-order quadrupolar shift. Using equations for the total shift observed at two field strengths, the chemical shift is uniquely determined together with a product of the quadrupolar coupling constant (C{sub Q} = e{sup 2}qQ/h) and the quadrupolar asymmetry parameter ({eta}). For one silicate, the authors demonstrate a computer program that uses the isotropic shifts and quadrupolar products as constraints and provides simulations of overlapped magic-angle spinning line shapes. In this way the quadrupolar parameters, C{sub Q} and {eta}, are determined separately for each crystallographic site. The silicates studied include the discrete orthosilicates larnite (Ca{sub 2}SiO{sub 4}) and forsterite (Mg{sub 2}SiO{sub 4}), as well as diopside (CaMgSi{sub 2}O{sub 6}), wollastonite (CaSiO{sub 3}), and clinoenstatite (MgSiO{sub 3}), which are minerals composed of chains of silicon-oxygen tetrahedra. 49 refs., 2 figs., 2 tabs.

Mueller, K.T.; Baltisberger, J.H.; Wooten, E.W.; Pines, A. [Lawrence Berkeley Laboratory, CA (United States)

1992-08-20

60

Molecular dynamics from 2H Quadrupolar Carr-Purcell-Meiboom-Gill solid-state NMR spectroscopy  

NASA Astrophysics Data System (ADS)

The 2H quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) NMR experiment is proposed as a convenient method to obtain detailed information about molecular dynamics in solids. Compared to the quadrupolar-echo (QE) experiment QCPMG offers two advantages. First, a sensitivity enhancement by about an order of magnitude is achieved by splitting the QE spectrum into spin-echo sidebands. Second, the lineshape of the individual sidebands provides detailed information about the molecular dynamics and increases the dynamic range by two orders of magnitude. The 2H QCPMG method is demonstrated experimentally and numerically using the two-fold flip process in dimethyl sulfone.

Larsen, Flemming H.; Jakobsen, Hans J.; Ellis, Paul D.; Nielsen, Niels Chr.

1998-08-01

61

Theoretical study of homonuclear J coupling between quadrupolar spins: single-crystal, DOR, and J-resolved NMR.  

PubMed

The theory describing homonuclear indirect nuclear spin-spin coupling (J) interactions between pairs of quadrupolar nuclei is outlined and supported by numerical calculations. The expected first-order multiplets for pairs of magnetically equivalent (A2), chemically equivalent (AA'), and non-equivalent (AX) quadrupolar nuclei are given. The various spectral changeovers from one first-order multiplet to another are investigated with numerical simulations using the SIMPSON program and the various thresholds defining each situation are given. The effects of chemical equivalence, as well as quadrupolar coupling, chemical shift differences, and dipolar coupling on double-rotation (DOR) and J-resolved NMR experiments for measuring homonuclear J coupling constants are investigated. The simulated J coupling multiplets under DOR conditions largely resemble the ideal multiplets predicted for single crystals, and a characteristic multiplet is expected for each of the A2, AA', and AX cases. The simulations demonstrate that it should be straightforward to distinguish between magnetic inequivalence and equivalence using J-resolved NMR, as was speculated previously. Additionally, it is shown that the second-order quadrupolar-dipolar cross-term does not affect the splittings in J-resolved experiments. Overall, the homonuclear J-resolved experiment for half-integer quadrupolar nuclei is demonstrated to be robust with respect to the effects of first- and second-order quadrupolar coupling, dipolar coupling, and chemical shift differences. PMID:24594753

Perras, Frédéric A; Bryce, David L

2014-05-01

62

Theoretical study of homonuclear J coupling between quadrupolar spins: Single-crystal, DOR, and J-resolved NMR  

NASA Astrophysics Data System (ADS)

The theory describing homonuclear indirect nuclear spin-spin coupling (J) interactions between pairs of quadrupolar nuclei is outlined and supported by numerical calculations. The expected first-order multiplets for pairs of magnetically equivalent (A2), chemically equivalent (AA?), and non-equivalent (AX) quadrupolar nuclei are given. The various spectral changeovers from one first-order multiplet to another are investigated with numerical simulations using the SIMPSON program and the various thresholds defining each situation are given. The effects of chemical equivalence, as well as quadrupolar coupling, chemical shift differences, and dipolar coupling on double-rotation (DOR) and J-resolved NMR experiments for measuring homonuclear J coupling constants are investigated. The simulated J coupling multiplets under DOR conditions largely resemble the ideal multiplets predicted for single crystals, and a characteristic multiplet is expected for each of the A2, AA?, and AX cases. The simulations demonstrate that it should be straightforward to distinguish between magnetic inequivalence and equivalence using J-resolved NMR, as was speculated previously. Additionally, it is shown that the second-order quadrupolar-dipolar cross-term does not affect the splittings in J-resolved experiments. Overall, the homonuclear J-resolved experiment for half-integer quadrupolar nuclei is demonstrated to be robust with respect to the effects of first- and second-order quadrupolar coupling, dipolar coupling, and chemical shift differences.

Perras, Frédéric A.; Bryce, David L.

2014-05-01

63

Optically detected nuclear quadrupolar interaction of N14 in nitrogen-vacancy centers in diamond  

NASA Astrophysics Data System (ADS)

We report sensitive detection of the nuclear quadrupolar interaction of the N14 nuclear spin of the nitrogen-vacancy (NV) center using the electron spin-echo envelope modulation technique. We applied a weak transverse magnetic field to the spin system so that certain forbidden transitions became weakly allowed due to second-order effects involving the nonsecular terms of the hyperfine interaction. The weak transitions cause modulation of the electron spin-echo signal, and a theoretical analysis suggests that the modulation frequency is primarily determined by the nuclear quadrupolar frequency; numerical simulations confirm the analytical results and show excellent quantitative agreement with experiments. This is an experimentally simple method of detecting quadrupolar interactions, and it can be used to study spin systems with an energy structure similar to that of the NV center.

Shin, Chang S.; Butler, Mark C.; Wang, Hai-Jing; Avalos, Claudia E.; Seltzer, Scott J.; Liu, Ren-Bao; Pines, Alexander; Bajaj, Vikram S.

2014-05-01

64

Determination of quadrupolar spin coupling for spin 7/2 using two pulse sequences  

NASA Astrophysics Data System (ADS)

The response of a spin 7/2 system subject to a first-order quadrupolar interaction and excited by two in-phase pulses separated by time delay is calculated ignoring high frequency terms. The results obtained are valid for any ratio of the quadrupolar coupling to the amplitude of an RF pulse. It is shown here that single- and multiple-quantum coherences developed during the first pulse can be detected at the end of the second pulse. Ot5h 1er pulse sequences with various phase cycling are also discussed. The results are applied to V nuclei in a single ferroelastic crystal of BiVO4.

Ageev, S. Z.; Man, P. P.; Fraissard, J.; Sanctuary, B. C.

65

Magnetic-field-induced shift of the optical band gap in Ni3V2O8  

NASA Astrophysics Data System (ADS)

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.

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

66

Magnetic-field-induced electron localisation in narrow-gap semimagnetic Hg1-xMnxTe  

Microsoft Academic Search

In order to shed some light on the controversy concerning the nature of the field-induced localisation in narrow-gap n-Hg1-xCdxTe, the authors have performed magnetoresistance and Hall effect measurements on n-Hg1-xMnxTe up to 140 kOe and down to 30 mK. For magnetic fields H below 50 kOe the role of the quantum corrections to the conductivity tensor components is pointed out.

J. Wrobel; T. Dietl; G. Karczewski; J. Jaroszynski; W. Plesiewicz; A. Lenard; M. Dybiec; M. Sawicki

1990-01-01

67

Origin of the magnetic field induced changes of the transverse plasma mode in the c-axis infrared response of underdoped Y Ba2Cu3O7-?  

NASA Astrophysics Data System (ADS)

We report on results of our theoretical study of magnetic field induced changes of the c-axis infrared response of bilayer cuprate superconductors using the phenomenological multilayer model involving the conductivity of the spacing layers and that of the bilayer units. For H perpendicular to the planes, the local conductivities have been expressed in terms of a two-fluid approximation—as weighted averages of the superconducting state ones and the normal state ones representing contributions of the vortex cores, the weight of the latter increasing linearly with the field. This allows us to reproduce and interpret the fast decrease with increasing H of the well known 400 cm-1 peak (transverse plasma mode) in the c-axis conductivity, observed by LaForge and co-workers. For the local conductivities of underdoped Y Ba2Cu3O7-? with Tc = 58 K reported by Dubroka and co-workers and the fraction of the normal state (T ? Tc) component given by (?0H/25 T), the computed field induced changes of the reflectivity are in quantitative agreement with the data. This suggests that the response at H = 0 and T ? Tc is close to that at H = 25 T < Hc2 and T ? Tc, in accord with theories attributing the above Tc state to that of a superconductor lacking long-range phase coherence. Also discussed are changes of the response induced by H parallel to the CuO2 planes.

Marek, J.; Munzar, D.

2011-10-01

68

Magnetic-field-induced spontaneous polarization reversal in multiferroic Mn0.85Co0.15WO4  

NASA Astrophysics Data System (ADS)

The magnetic and ferroelectric properties of the multiferroic system Mn1-xCoxWO4 (x =0.135, 0.15, and 0.17) are studied in magnetic fields Hc oriented along the monoclinic c axis. Mn0.85Co0.15WO4, which is right at the phase boundary between two helical spin structures, exhibits a spontaneous sign change of the ferroelectric polarization when cooled in fields Hc> 25 kOe. The origin of the ferroelectric polarization is studied and two magnetic exchange interactions contributing to the polarization are identified. In Mn0.85Co0.15WO4, domains of the characteristic helical spin structures, known for x <0.15 and x >0.15, coexist and form domain boundaries. The contributions of the different domains to the global polarization are determined. The polarization reversal in Mn0.85Co0.15WO4 can be explained by a combination of various contributions to the polarization and a strong correlation between magnetic domains of different helical spin orders resulting in a smooth transition across the domain walls, which preserves the chirality of the spin spiral.

Poudel, N.; Liang, K.-C.; Wang, Y.-Q.; Sun, Y. Y.; Lorenz, B.; Ye, F.; Fernandez-Baca, J. A.; Chu, C. W.

2014-02-01

69

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

SciTech Connect

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.

Basova, Tamara, E-mail: basova@niic.nsc.ru; Berezin, Aleksei; Nadolinny, Vladimir [Nikolaev Institute of Inorganic Chemistry, Russian Academy of Sciences, Lavrentiev Pr., 3, 630090 Novosibirsk (Russian Federation)] [Nikolaev Institute of Inorganic Chemistry, Russian Academy of Sciences, Lavrentiev Pr., 3, 630090 Novosibirsk (Russian Federation); Peisert, Heiko; Chassé, Thomas [Institute for Physical and Theoretical Chemistry, Auf der Morgenstelle 18, 72076 Tübingen (Germany)] [Institute for Physical and Theoretical Chemistry, Auf der Morgenstelle 18, 72076 Tübingen (Germany); Banimuslem, Hikmat; Hassan, Aseel [Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1WB (United Kingdom)] [Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1WB (United Kingdom)

2013-11-28

70

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

71

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

PubMed

The ?-(oxo)bis[tetra-tert-butylphthalocyaninato] aluminum(III) [(tBu)4PcAl]2O films with the crystallites oriented preferably in one direction were obtained via chemical transformation of tetra-tert-butylsubstituted chloroaluminum(III) phthalocyanine (tBu)4PcAlCl film upon its annealing in magnetic field. A comparative analysis of the influence of post-deposition annealing process without and under applied magnetic field of 1 T, on the orientation and morphology of (tBu)4PcAlCl and [(tBu)4PcAl]2O films, has been carried out by the methods of UV-vis, Infrared and Raman spectroscopies, XRD as well as atomic force microscopy. The formation of [(tBu)4PcAl]2O films with elongated crystallites having preferential orientation was observed upon heating of the films in magnetic field while annealing without magnetic field under the same conditions does not demonstrate any effect on the structure and morphology of these films. The reasons of the sensitivity of this reaction to the presence of such magnetic field is discussed and studied by electronic paramagnetic resonance spectroscopy. PMID:24289372

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

2013-11-28

72

Spin temperature applied to an inhomogeneously broadened pure quadrupolar resonance  

NASA Astrophysics Data System (ADS)

The application of the spin-temperature hypothesis to inhomogeneously broadened pure quadrupolar resonances is dependent on the identification of appropriate quasi-invariants. Three models of inhomogeneity in the dominant quadrupolar spin coupling are discussed and employed to predict the spin response to the modified Jeener-Broekaert multiple-pulse sequence. The set of generators for the SU(4) Lie algebra is used to calculate the evolution of the quadrupolar spin system in the interaction representation in the presence of a pulsed radiofrequency perturbation. The theoretical predictions are compared to experimental observations of the response of the chlorine spin system in polycrystalline and single-crystal samples of the cubic antifluorite, K2OsCl6 at 295 and 77 K. A description of the inhomogeneity involving finite domains of spins with a common strength of the quadrupolar coupling is shown to be successful in accounting for the observations.

Singh, Marsha A.; Armstrong, Robin L.

1988-07-01

73

Relaxation times of spin states of all ranks and orders of quadrupolar nuclei estimated from NMR z-spectra: Markov chain Monte Carlo analysis applied to 7Li+ and 23Na+ in stretched hydrogels.  

PubMed

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

Kuchel, Philip W; Naumann, Christoph; Puckeridge, Max; Chapman, Bogdan E; Szekely, David

2011-09-01

74

SIMQUADNMR: a program for simulation and interpretation of multiple quantum-filtered NMR spectra of quadrupolar nuclei  

Microsoft Academic Search

In this paper, we present a computer program which simulates NMR multiple quantum-filtered spectra of quadrupolar nuclei as a function of physical parameters, of the type of experiment and experimental conditions. The program works by solving relaxation theory equations for the given system, and it can be useful in order to plan the ideal conditions to set up specific experiments

Nicola D’Amelio; Elena Gaggelli; Elena Molteni; Gianni Valensin

2005-01-01

75

Quadrupolar spin relaxation due to electric field gradients induced by vibrations and collisions  

NASA Astrophysics Data System (ADS)

The spin relaxation of quadrupolar nuclei in highly symmetric electronic environments via vibrationally-induced electric field gradients is considered. A model is presented for tetrahedral molecules which yields a nuclear quadrupole coupling constant for 189Os in an excited vibrational state of OsO4 which is in reasonable agreement with experimentally observed values. The nuclear quadrupole coupling constants for the central nucleus in excited E and F2 vibrational states of GeCl4, GeBr4, RuO4, OsO4 molecules as well as the MOn-4 ions (M = V, Cr, Mn, Mo, Tc, Re) are calculated using this model. These coupling constants lead to quadrupolar relaxation rates which are orders of magnitude too small compared to experiment. Alternate mechanisms, collisional-deformation by long-range van der Waals interactions and fields induced by octopole moments, are proposed. A binary collision model is used in which the fluctuating electric fields associated with London dispersion forces during a collision create electric field gradients at the quadrupolar nucleus. Parallel development of vibrational and intermolecular effects on nuclear shielding with vibrational and collisional-deformation-induced electric field gradients is shown. The latter mechanism and the octopole-induced fields are capable of giving relaxation rates of the right order of magnitude.

Osten, H. Jörg; Jameson, Cynthia J.

76

Magnetic-field-induced localization in narrow-gap semiconductors Hg/sub 1-//sub x/Cd/sub x/Te and InSb  

SciTech Connect

Magnetotransport measurements on n-type Hg/sub 1-//sub x/Cd/sub x/Te (xapprox. =0.2) and InSb and far-infrared magnetooptical spectroscopy in Hg/sub 1-//sub x/Cd/sub x/Te are reported. The transport data at magnetic fields below and near the magnetic-field-induced metal-insulator (M-I) transition indicate clear similarity of Hg/sub 1-//sub x/Cd/sub x/Te and InSb. At fields well above the M-I transition and at low temperatures, the magnetotransport coefficients for Hg/sub 1-//sub x/Cd/sub x/Te show anomalously weak dependences on field and temperature. This is attributed to shorting of the bulk by a conducting surface layer. Below the M-I transition field, an anomalous Hall effect is observed in both Hg/sub 1-//sub x/Cd/sub x/Te and InSb. We interpret this effect within a model in which the M-I transition takes place in the donor impurity band. The impurity cyclotron resonance observed in Hg/sub 1-//sub x/Cd/sub x/Te provides conclusive evidence for donor-bound electrons in this semiconductor and further confirms its similarity to InSb. The cyclotron-resonance data are in agreement with theoretical predictions for hydrogenic donors in a strong magnetic field. These observations provide strong evidence against the Wigner crystallization of electrons in Hg/sub 1-//sub x/Cd/sub x/Te.

Shayegan, M.; Goldman, V.J.; Drew, H.D.

1988-09-15

77

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

NASA Astrophysics Data System (ADS)

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

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

1997-11-01

78

Mean-field model for the quadrupolar phases of UPd3  

NASA Astrophysics Data System (ADS)

UPd3 is known to exhibit four antiferroquadrupolar ordered phases at low temperatures. We report measur-ements of the magnetization and magnetostriction of single crystal UPd3, along the principal symmetry directions, in fields up to 33 T. These results have been combined with recent inelastic neutron and x-ray resonant scattering measurements to construct a mean-field model of UPd3 including up to fourth nearest-neighbor interactions. In particular, we find that anisotropic quadrupolar interactions must be included in order to explain the low-temperature structures derived from the scattering data.

Le, Manh Duc; McEwen, Keith A.; Rotter, Martin; Doerr, Mathias; Barcza, Alexander; Park, Je-Geun; Brooks, James; Jobiliong, Eric; Fort, David

2014-06-01

79

Possible observation of quadrupolar Kondo effect in Pr-based dilute quadrupolar compounds  

NASA Astrophysics Data System (ADS)

We have studied the low-temperature properties of PrxLa1-xPb3 and PrxLa1-xlnAg2 with the crystal-electric-field (CEF) ground state of a non-Kramers ?3 doublet. In PrxLa1-xPb3, non-Fermi-liquid (NFL) behavior has been observed for Pr concentrations x?0.05 in the specific heat C/T, susceptibility and electrical resistivity at low temperatures. Moreover, application of magnetic field raises C/T rapidly, which demonstrates the presence of the residual entropy at lower temperatures. In PrxLa1-xlnAg2, characteristic features have been seen up to x=0.8 in the susceptibility and specific heat below 15 K. These behaviors can be caused by the quadrupolar Kondo effect arising from the correlation between the dilute ?3 moments and the conduction electrons.

Kawae, T.; Nakaie, Y.; Inagaki, Y.; Hidaka, M.; Tateiwa, N.; Kitai, T.

2007-03-01

80

Quantum Phases of Quadrupolar Fermi Gases in Optical Lattices  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

81

Surface and Subsurface Quadrupolar Probes for Future Space Missions  

Microsoft Academic Search

Quadrupolar Probes (also called Mutual Impedance Probes) can accurately measure the electrical properties of gaseous, solid and liquid materials. Flight instruments have been developed for atmospheric investigations (Huygens) and for stationary surface measurements (Rosetta lander). Future space missions will employ mobile platforms such as surface vehicles and underground tools (drills, moles). These new instrument carriers will require adapted electrode configurations

R. Trautner; F. Simões; R. Grard; M. Hamelin

2003-01-01

82

The combined effect of quadrupolar and dipolar interactions on the excitation and evolution of triple quantum coherences in ?Li solid state magic angle spinning NMR.  

PubMed

Magic-angle spinning triple-quantum NMR spectra of lithium-7 provide enhanced spectral dispersion for the inherent low chemical shift range of this nucleus, while maintaining linewidths, which are free of any quadrupolar broadening to first order. Since the quadrupolar interaction of (7)Li is very small, in the order of the radio frequency nutation frequencies and only moderately larger than the spinning rates, such spectra are also only marginally affected by the second order quadrupolar interaction under large magnetic fields. In the current study we demonstrate that the existence of two and more proximate (7)Li spins, as encountered in many materials, affects both excitation and evolution of triple-quantum coherences due to the combined effect of quadrupolar and homonuclear dipolar interactions. We show that the generation of (7)Li triple-quantum coherences using two ?/2 pulses separated by one-half rotor period is superior in such cases to a single pulse excitation since the excitation time is shorter; thus the maximum signal is only marginally affected by the homonuclear dipolar couplings. When the quadrupolar-dipolar cross terms dominate the spectra, single- and triple-quantum lineshapes are very similar and therefore a true gain in dispersion is maintained in the latter spectrum. The effects of quadrupolar-dipolar cross terms are experimentally demonstrated by comparing a natural abundance and a (6)Li-diluted samples of lithium acetate, resulting in the possibility of efficient excitation of triple quantum coherences over longer periods of time, and in longer life times of triple-quantum coherences. PMID:23481861

Eliav, Uzi; Goldbourt, Amir

2013-05-01

83

Dielectrophoretic manipulation of finite sized species and the importance of the quadrupolar contribution  

NASA Astrophysics Data System (ADS)

Dielectrophoresis (DEP) is the movement of polarizable species in a nonuniform electric field. DEP is used to attract (positive DEP) to or repel from (negative DEP) regions of high field intensity and is useful for manipulating species, including biological species. Current theoretical and numerical approaches used to predict the response to DEP forces assume that the target species is a point particle; however, in practice, the target species is of finite size, e.g., macromolecules, spores and assay beads. To elucidate the importance of target species size effects, higher order terms in the DEP force multipole expansion must be considered [P.R.C. Gascoyne and J. Vykoukal, Electrophoresis 23, 1973 (2002)]. In this paper, we used the method of Green’s function to derive and explore the importance of the quadrupolar contribution to the DEP forces acting on finite-sized species produced by a planar, interdigitated array of electrodes. Based on the analysis, it was found, for example, that at a fixed height of 20 ?m in an interdigitated DEP array with an electrode width and spacing of 20 ?m energized by a 10 Vp p, 1.0 MHz ac signal, the quadrupolar contribution to the total DEP force was 5% for a latex bead with 4.2 ?m in radius and 10% for the one with 6 ?m in radius. For a fixed, fractional quadrupolar contribution, ? , both the exact calculation and the scaling estimate elucidate that the critical size of particle increase linearly with the electrode width (and spacing) at a fixed height, while the critical particle radius increases with a square-root dependence on the width height above the electrode in the electrode array.

Liang, Enzhu; Smith, Rosemary L.; Clague, David S.

2004-12-01

84

Magnetic relaxation of quadrupolar nuclei in nonaqueous electrolyte solutions  

Microsoft Academic Search

The NMR relaxation times of the quadrupolar nuclei 7Li, 23Na, 87Rb, and 133Cs in electrolyte solutions in methanol have been measured with pulse and wide-line techniques. In addition, 87Rb relaxation rates were obtained in solutions of RbF in ethanol, ethylene glycol, and formamide. The data were used to test an electrostatic relaxation theory in the limit of infinite dilution. The

C. A. Melendres; H. G. Hertz

1974-01-01

85

NMR spin-lattice relaxation in the deuterium quadrupolar glass  

Microsoft Academic Search

We present measurements of nuclear spin-lattice relaxation in solid D2 for para concentrations 0.24quadrupolar glass state. A model of para-ortho cross relaxation is presented which allows our D2 data to be compared with previous H2 relaxation data.

Donald Candela; Saps Buchman; W. T. Vetterling; R. V. Pound

1983-01-01

86

Two-dimensional nuclear magnetic resonance of quadrupolar systems  

SciTech Connect

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

Wang, Shuanhu

1997-09-17

87

Nonresonant Photon Dressing in Spin One Quadrupolar Systems  

NASA Astrophysics Data System (ADS)

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

Zhuang, Yi-Li.

88

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

SciTech Connect

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

Karpinska, K.; Malinowski, A.; Cieplak, M.Z.; Guha, S.; Gershman, S.; Kotliar, G.; Skoskiewicz, T.; Plesiewicz, W.; Berkowski, M.; Lindenfeld, P. [Institute of Physics, Polish Academy of Sciences, 02 668 Warsaw (Poland)] [Institute of Physics, Polish Academy of Sciences, 02 668 Warsaw (Poland); [Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08855 (United States)

1996-09-01

89

Dipolar and Quadrupolar Modes of SiO2/Au Nanoshell Enhanced Light Trapping in Thin Film Solar Cells  

NASA Astrophysics Data System (ADS)

Dipolar and quadrupolar resonance wavelengths of SiO2/Au nanoshell surface plasmons are designed at 560 nm to enhance the light trapping in thin film solar cells. In order to quantitatively describe the light trapping effect, the forward-scattering efficiency (FSE) and the light trapping efficiency (LTE) are proposed by considering the light scattering direction of SiO2/Au nanoshells. Based on the Mie theory, the FSE and the LTE are calculated for SiO2/Au nanoshells of different dimensions, and the contributions of the dipolar and quadrupolar modes to the light trapping effect are analyzed in detail. When the surface coverage of nanoshells is 5%, the LTEs are 21.7% and 46.9% for SiO2/Au nanoshells with sizes of (31 nm, 69 nm) and (53 nm, 141 nm), respectively. The results indicate that the SiO2/Au nanoshell whose quadrupolar mode peak is designed to the strongest solar energy flux density of the solar spectrum facilitates the further enhancement of light harvesting in thin film solar cells.

Bai, Yi-Ming; Wang, Jun; Chen, Nuo-Fu; Yao, Jian-Xi; Zhang, Xing-Wang; Yin, Zhi-Gang; Zhang, Han; Huang, Tian-Mao

2011-08-01

90

Quadrupolar Kondo effect in uranium heavy-electron materials?  

NASA Technical Reports Server (NTRS)

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

Cox, D. L.

1987-01-01

91

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

SciTech Connect

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

Visser, D. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)] [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Monteith, A.R. [The Royal Institution of Great Britain, 21 Albemarle Street, London W1X 4BS (United Kingdom)] [The Royal Institution of Great Britain, 21 Albemarle Street, London W1X 4BS (United Kingdom); Bargawi, A.Y. [Department of Physics, Umm Al-Qura University, Makkah (Saudi Arabia)] [Department of Physics, Umm Al-Qura University, Makkah (Saudi Arabia); Zeiske, T. [BENSC, Hahn Meitner Institut, Glienecker Strasse 100, Berlin (Germany)] [BENSC, Hahn Meitner Institut, Glienecker Strasse 100, Berlin (Germany)

1997-04-01

92

Nuclear Magnetic Relaxation in METHYLENE-13 and METHYL-13 Coupled Spin Systems and Variable Angle Spinning Lineshape Analysis for Quadrupolar Nuclei with Half Integer Spins  

NASA Astrophysics Data System (ADS)

The carbon-13 multiplet spin-lattice relaxation in ^{13}CH_2 and ^{13}CH _3^in systems is studied in detail by various nonselective and selective pulse techniques. Simultaneous fitting of the resulting relaxation curves with various rates and initial conditions allows for the extraction of both auto- and cross-correlated dipolar spectral densities which can provide detailed information on the molecular anisotropic reorientation. In addition, the ^ {13}CH_3 coupled spin relaxation can characterize the methyl internal rotation dynamics. The cross-correlation between the dipolar and chemical shift anisotropy (CSA) interactions is found to be appreciable. Dipolar-CSA cross-correlated spectral densities introduce relaxation pathways that couple together magnetization modes with different spin inversion symmetries. Consideration of the dipolar-CSA cross-correlated spectral densities not only improves the accuracy of the measurement of dipolar spectral densities but also allows for the determination of the dipolar-CSA cross-correlated spectral densities themselves, providing a new measure of the anisotropy of the shielding tensor. NMR spectroscopy of quadrupolar nuclei in solids generally yields broad lines even when magic angle spinning is applied. Broadening of the central transition of quadrupolar nuclei with half integer spins is caused by the anisotropy of the second order quadrupolar interaction. A straightforward approach is presented that combines average Hamiltonian theory and a numerical solution of a classical banded matrix describing the equation of motion for a quadrupolar nucleus under variable angle sample spinning conditions. At either of two fourth rank magic angles, a simple three parameter lineshape is obtained, and the three breakpoints are related directly to the quadrupolar constant and its asymmetry parameter. The banded matrix method used in the simulations is computationally much more efficient than the standard method using Bessel functions.

Zheng, Zhiwen

1992-01-01

93

Magnetic Field-Induced Phase Transitions in the S=1/2 Two-Leg Spin-Ladder Material Cu(DEP)Br2  

NASA Astrophysics Data System (ADS)

From heat capacity (Cp) measurements on a single crystal sample of the spin (S) 1/2 two-leg spin-ladder material Cu(DEP)Br2 above a critical magnetic field (Hc0) where the energy gap between the singlet ground state and the excited magnetic state closes, we have observed a peak anomaly, which is indicative of a magnetic long-range ordering. We have examined how the position of the anomaly in Cp changes with temperature (T) and magnetic field (H) to obtain the experimental H--T phase diagram of this S=1/2 two-leg spin ladder material. From the low-temperature specific heat below Hc0, we have evaluated the field-dependent energy gap that vanishes at about 7.6 T.

Honda, Zentaro; Katori, Hiroko Aruga; Ikeda, Masami; Hagiwara, Masayuki; Okunishi, Kouichi; Sakai, Masamichi; Fukuda, Takeshi; Kamata, Norihiko

2012-11-01

94

Toroidal current induced by particle trapping inside a new toroidal laboratory magnetized plasma device with poloidal magnetic field induced by a central conductor  

NASA Astrophysics Data System (ADS)

In the laboratory toroidal device MISTOR, a poloidal field is created by a current (1200 A) flowing along a central toroidal conductor. A security factor q=1 is obtained at radial position r = 5 cm. Helium plasma is produced by electric discharge using a tungsten filament. When Bpol= 0, the whole plasma is turbulent that is a standard in a Simple Magnetized Torus. As Bpol is increased, the turbulence level decreases and a stable plasma is obtained. This is correlated with the decrease of the radial electric field. The confinement time is estimated in the afterglow decaying plasma. It increases from 50 microsec. without poloidal field to 0.5 millisec. when q=1 at mid-radius. The trapping of the particles inside the mirror-traps inherent in this topology (banana orbits) is studied. The precession of the banana orbits seems to be the dominant mechanism. The measurement of the toroidal current using a probe indicates that the electrons experience an oriented toroidal drift along the field lines. Detailed measurements of the EEDF are compared with theory. The influence of detrapping is investigated in order to estimate the bootstrap current induced in this device.

Pierre, Th.; Caron, X.; Gravier, E.; Antar, G.

2012-10-01

95

Averaging methods applied to quadrupolar FT-ICR perturbation problems  

NASA Astrophysics Data System (ADS)

Many FT-ICR systems are approximately described by single ion motion in a constant magnetic field and a quadratic electrostatic potential. In this study, the quadrupole approximation--a magnetic field combined with a quadratic trapping potential--is considered the unperturbed problem while all other forces are treated as perturbations to this motion. Transformations are derived for the equations of motion describing the time variation of the constants of motion of the quadrupole problem. Reformulation of the quadrupolar problem in these variables can offer significant analytical and numerical advantages. In this form approximate analytical solutions to the perturbed problem are obtainable by averaging methods. Numerical integration of the transformed equations can give directly the time-dependence of the mode amplitudes and instantaneous frequencies. Applications of the theory include the derivation of frequency shifts, approximate invariants and the equations of motion describing non-linear resonance.

Mitchell, Dale W.

1991-08-01

96

The Percus-Yevick approximation for quadrupolar molecular fluids.  

PubMed

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

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

2009-03-18

97

Charge instability of symmetry broken dipolar states in quadrupolar and octupolar triphenylamine derivatives.  

PubMed

The quadrupolar and octupolar cyano triphenylamines shows symmetry broken dipolar charge transfer state, however, its stability can be controlled by the rotation of N-C bond of amino and phenylene moiety. PMID:24840223

Easwaramoorthi, Shanmugam; Thamaraiselvi, Pichandi; Duraimurugan, Kumaraguru; Beneto, Arockiam Jesin; Siva, Ayyanar; Nair, Balachandran Unni

2014-06-01

98

Nuclear quadrupolar spin-lattice relaxation in some III-V compounds  

Microsoft Academic Search

Measurements of the spin-lattice relaxation rates in the group-III-V compounds, GaAs, GaSb, InAs, and InSb, are presented as a function of temperature from 4 to 300 K. These rates, except for GaSb, are separated into magnetic and quadrupolar parts. The quadrupolar rates are separated into relaxation by acoustic phonons and that by optical phonons. A simple phenomenological model fits the

John A. McNeil; W. Gilbert Clark

1976-01-01

99

Detailed analysis of the S-RESPDOR solid-state NMR method for inter-nuclear distance measurement between spin-1/2 and quadrupolar nuclei.  

PubMed

We present a detailed analysis of the Symmetry-based Resonance-Echo Saturation-Pulse DOuble-Resonance (S-RESPDOR) method in order to measure the inter-nuclear distances between spin-1/2 and quadrupolar nuclei. This recently introduced sequence employs a symmetry-based recoupling scheme on the observed spin-1/2 channel and a saturation pulse on the quadrupolar channel. This method requires a low radio-frequency (rf) field, is compatible with high MAS frequency and allows a rapid determination of inter-nuclear distances by fitting the experimental signal fraction to an analytical expression. Here, we analyze in detail the influence of the various experimental and spin-interaction parameters on the S-RESPDOR signal fraction and the measured distance. We show that the S-RESPDOR signal fraction only depends on the quadrupole interaction and the inter-nuclear distance. We demonstrate that the required rf-field on the quadrupolar channel is smaller than that required for an adiabatic-passage pulse in REAPDOR-type experiments. The only limitation of the method is the requirement of accurate rotor synchronization between the two parts of the dipolar recoupling sequences. Using S-RESPDOR, we have quantitatively measured a (31)P-(51)V distance of 357 pm in a mono-vanadium-substituted polyoxo-tungstate, K(4)PVW(11)O(40), from the Keggin family and a (13)C-(67)Zn distance of 286 pm in [80%-(67)Zn]zinc [1-(13)C]acetate. These results show that S-RESPDOR can be employed in the challenging cases of quadrupolar nuclei exhibiting a high spin number and either large chemical-shift anisotropy ((51)V) or low gyromagnetic ratio ((67)Zn). PMID:22257437

Lu, Xingyu; Lafon, Olivier; Trébosc, Julien; Amoureux, Jean-Paul

2012-02-01

100

Dipolar and quadrupolar detection using an FT-ICR MS setup at the MPIK Heidelberg  

NASA Astrophysics Data System (ADS)

Dipolar and single-phase two-electrode quadrupolar detection schemes have been investigated at a Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) setup built for the KATRIN experiment at the Max-Planck-Institute for Nuclear Physics (MPIK) in Heidelberg. We present first experimental results of 7Li + signals from a cylindrical Penning trap configuration for both detection schemes. While the prominent signal of the conventional dipolar detection scheme marks the reduced cyclotron frequency, the main signal for the quadrupolar detection appears at the sum of the reduced cyclotron frequency and the magnetron frequency. For ideal trapping fields, this sum frequency equals the ion cyclotron frequency ? c = qB/(2 ?m). Sidebands due to the combined motions of the cyclotron mode and magnetron mode are observed by quadrupolar detection which allows the determination of the respective combinations of eigenfrequencies.

Heck, Michael; Blaum, Klaus; Cakirli, R. Burcu; Rodríguez, Daniel; Schweikhard, Lutz; Stahl, Stefan; Ubieto-Díaz, Marta

2011-07-01

101

Quantum logical operations for spin 3/2 quadrupolar nuclei monitored by quantum state tomography.  

PubMed

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

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

102

NMR evidence for higher-order multipole order parameters in NpO2.  

PubMed

We report a microscopic investigation of multipolar order parameters in the ordered state of NpO2 conducted via 17O NMR on a single crystal. From the angular dependence of hyperfine fields at 17O nuclei, we have obtained clear evidence for the appearance of field-induced antiferro-octupolar as well as field-induced antiferro-dipolar moments below T0 = 26 K. We have also observed oscillatory spin-echo decay, which is well understood in terms of small electric field gradients created by antiferro-quadrupolar ordering. This reveals that the quadrupolar order parameter is directly observable by means of NMR. The present NMR studies provide definitive support for a proposed longitudinal triple-q type octupolar-quadrupolar ordering model for NpO2. PMID:17280392

Tokunaga, Y; Aoki, D; Homma, Y; Kambe, S; Sakai, H; Ikeda, S; Fujimoto, T; Walstedt, R E; Yasuoka, H; Yamamoto, E; Nakamura, A; Shiokawa, Y

2006-12-22

103

Conformational response of the phosphatidylcholine headgroup to bilayer surface charge: torsion angle constraints from dipolar and quadrupolar couplings in bicelles.  

PubMed

The effects of bilayer surface charge on the conformation of the phosphocholine group of phosphatidylcholine were investigated using a torsion angle analysis of quadrupolar and dipolar splittings in, respectively, (2)H and (13)C NMR spectra of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) labelled in the phosphocholine group with either deuterons (POPC-alpha-d(2), POPC-beta-d(2) and POPC-gamma-d(9)) or carbon-13 (POPC-alpha-(13)C and POPC-alphabeta-(13)C(2)) and incorporated into magnetically aligned bicelles containing various amounts of either the cationic amphiphile 1,2-dimyristoyl-3-trimethylammoniumpropane (DMTAP) or the anionic amphiphile 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG). Three sets of quadrupolar splittings, one from each of the three deuteron labelling positions, and three sets of dipolar splittings ((13)C(alpha)-(31)P, (13)C(alpha)-(13)C(beta), (13)C(beta)-(14)N), were measured at each surface charge, along with the (31)P residual chemical shift anisotropy. The torsion angle analysis assumed fast anisotropic rotation of POPC about its long molecular axis, thus projecting all NMR interactions onto that director axis of motion. Dipolar, quadrupolar and chemical shift anisotropies were calculated as a function of the phosphocholine internal torsion angles by first transforming into a common reference frame affixed to the phosphocholine group prior to motional averaging about the director axis. A comparison of experiment and calculation provided the two order parameters specifying the director orientation relative to the molecule, plus the torsion angles alpha(3), alpha(4) and alpha(5). Surface charge was found to have little effect on the torsion angle alpha(5) (rotations about C(alpha)-C(beta)), but to have large and inverse effects on torsion angles alpha(3) [rotations about P-O(11)] and alpha(4) [rotations about O(11)-C(alpha)], yielding a net upwards tilt of the P-N vector in the presence of cationic surface charge, and a downwards tilt in the presence of anionic surface charge, relative to neutrality. PMID:14745788

Semchyschyn, Darlene J; Macdonald, Peter M

2004-02-01

104

Possible Observation of the Quadrupolar Kondo Effect in Dilute Quadrupolar System PrxLa1-xPb3 for x<=0.05  

Microsoft Academic Search

We have studied non-Fermi-liquid (NFL) behavior in PrxLa1-xPb3 with Gamma3 quadrupolar moments in the crystalline-electric-field ground state. The specific heat C\\/T shows NFL behavior in the very dilute region for x<=0.05, which is scaled by a characteristic temperature T* in each Pr concentration. The application of a magnetic field leads to a sharp increase of C\\/T, demonstrating the shift of

T. Kawae; K. Kinoshita; Y. Nakaie; N. Tateiwa; K. Takeda; H. S. Suzuki; T. Kitai

2006-01-01

105

Energy Interchange between Cyclotron and Synchronous Waves in Quadrupolar Pump Fields  

Microsoft Academic Search

Passive coupling of the electron cyclotron and synchronous waves in quadrupolar pump fields is examined. It is shown that sinusoidal energy exchange occurs when the quadrupole field is pumped so that the effective or Doppler-shifted pump frequency as observed by the drifting beam equals the electron cyclotron frequency. One fast and one slow wave are coupled when the pump frequency

E. I. Gordon; A. Ashkin

1961-01-01

106

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

PubMed

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

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

2010-09-01

107

Coexistence of ferromagnetic and antiferromagnetic order in Mn-doped Ni2MnGa  

Microsoft Academic Search

Ni-Mn-Ga is interesting as a prototype of a magnetic shape-memory alloy showing large magnetic-field-induced strains. We present here results for the magnetic ordering of Mn-rich Ni-Mn-Ga alloys based on both experiments and theory. Experimental trends for the composition dependence of the magnetization are measured by a vibrating sample magnetometer in magnetic fields of up to several tesla and at low

J. Enkovaara; O. Heczko; A. Ayuela; R. M. Nieminen

2003-01-01

108

27Al NMR experiments and quadrupolar parameter ab initio calculations: Crystallographic structure refinement of ?-Ba 3AlF 9  

Microsoft Academic Search

27Al quadrupolar parameters are determined for the three aluminium sites in ?-Ba3AlF9 from the reconstruction of experimental SATRAS and MQ-MAS NMR spectra. These quadrupolar parameters are then computed using the DFT linearized augmented plane wave method implemented in the WIEN2k code.A fine agreement between experimental and calculated values is obtained only after optimizing the ?-Ba3AlF9 structure. The optimized structure is

M. Body; G. Silly; C. Legein; J.-Y. Buzaré; F. Calvayrac; P. Blaha

2006-01-01

109

Perturbed chain-statistical associating fluid theory extended to dipolar and quadrupolar molecular fluids.  

PubMed

The perturbed chain statistical associating fluid theory (PC-SAFT) is extended to polar molecular fluids, namely dipolar and quadrupolar fluids. The extension is based on the perturbation theory for polar fluids by Stell and co-workers. Appropriate expressions are proposed for dipole-dipole, quadrupole-quadrupole, and dipole-quadrupole interactions. Furthermore, induced dipole interactions are calculated explicitly in the model. The new polar PC-SAFT model is relatively complex; for this purpose, a truncated polar PC-SAFT model is proposed using only the leading term in the polynomial expansion for polar interactions. The new model is used for the calculation of thermodynamic properties of various quadrupolar pure fluids. In all cases, the agreement between experimental data and model predictions is very good. PMID:16671742

Karakatsani, Eirini K; Economou, Ioannis G

2006-05-11

110

Off-angle correlation spectroscopy applied to spin-1/2 and quadrupolar nuclei.  

PubMed

A two-dimensional correlation experiment is described, in which homonuclear dipolar couplings are used to realize through-space magnetization exchange on spin-1/2 (31P) and on quadrupolar nuclei (23Na and 11B). In the detection period, Magic Angle Spinning is applied to enhance resolution, and the dipole couplings are re-introduced in the mixing period by spinning off the Magic Angle. The dependency of the exchange rates on the mixing time and the spinning angle is investigated. The influence of strong spin-locking during mixing is discussed, and shown in the spin-1/2 case to remove the dependence on chemical shift offset effects. For quadrupolar spins, the experiment yields information on the relative tensor orientations of the coupled quadrupoles. Applications to crystalline sodium aluminum diphosphate, sodium sulphite, and potassium borate glasses are shown. PMID:10378433

Hartmann, P; Jäger, C; Zwanziger, J W

1999-05-01

111

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

112

Quadrupolar correlations and deformation effects on nuclear transition matrix elements of double-{beta} decay  

SciTech Connect

The effect of quadrupolar correlations vis-a-vis deformation on the nuclear transition matrix elements of two neutrino and neutrinoless {beta}{beta} decay is studied in the PHFB model. It is observed that the deformation effects scale almost similarly for both the two neutrino and neutrinoless {beta}{beta} decay modes and the independent deformations of initial and final nuclei are important parameters to describe the nuclear transition matrix elements for different modes of {beta}{beta} decay.

Rath, P. K. [Department of Physics, University of Lucknow, Lucknow-226007 (India)

2009-11-09

113

High-Resolution NMR of Quadrupolar Nuclei in the Solid State  

SciTech Connect

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.

Gann, Sheryl Lee

1995-11-30

114

Off-angle correlation spectroscopy applied to spin-1\\/2 and quadrupolar nuclei  

Microsoft Academic Search

A two-dimensional correlation experiment is described, in which homonuclear dipolar couplings are used to realize through-space magnetization exchange on spin-1\\/2 (31P) and on quadrupolar nuclei (23Na and 11B). In the detection period, Magic Angle Spinning is applied to enhance resolution, and the dipole couplings are re-introduced in the mixing period by spinning off the Magic Angle. The dependency of the

P Hartmann; C Jäger; J. W Zwanziger

1999-01-01

115

Photoinduced symmetry-breaking intramolecular charge transfer in a quadrupolar pyridinium derivative.  

PubMed

We report here a joint experimental and theoretical study of a quadrupolar, two-branched pyridinium derivative of interest as a potential non-linear optical material. The spectral and photophysical behaviour of this symmetric system is greatly affected by the polarity of the medium. A very efficient photoinduced intramolecular charge transfer, surprisingly more efficient than in the dipolar asymmetric analogue, is found to occur by femtosecond resolved transient absorption spectroscopy. TD-DFT calculations are in excellent agreement with these experimental findings and predict large charge displacements in the molecular orbitals describing the ground state and the lowest excited singlet state. The theoretical study also revealed that in highly polar media the symmetry of the excited state is broken giving a possible explanation to the fluorescence and transient absorption spectra resembling those of the one-branched analogous compound in the same solvents. The present study may give an important insight into the excited state deactivation mechanism of cationic (donor-?-acceptor-?-donor)(+) quadrupolar compounds characterised by negative solvatochromism, which are expected to show significant two-photon absorption (TPA). Moreover, the water solubility of the investigated quadrupolar system may represent an added value in view of the most promising applications of TPA materials in biology and medicine. PMID:24898848

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

2014-07-21

116

Accretion-driven gravitational radiation from nonrotating compact objects: Infalling quadrupolar shells  

NASA Astrophysics Data System (ADS)

This paper reports results from numerical simulations of the gravitational radiation emitted from non-rotating compact objects (both neutron stars and Schwarzschild black holes) as a result of the accretion of matter. We adopt a hybrid procedure in which we evolve numerically, and assuming axisymmetry, the linearized equations describing metric and fluid perturbations coupled to a fully nonlinear hydrodynamics code that calculates the motion of the accreting matter. The initial matter distribution, which is initially at rest, is shaped in the form of extended quadrupolar shells of either dust or obeying a perfect fluid equation of state. Self-gravity of the accreting layers of fluid is neglected, as well as radiation reaction effects. We use this idealized setup in order to understand the qualitative features appearing in the energy spectrum of the gravitational wave emission from compact stars or black holes, subject to accretion processes involving extended objects. A comparison for the case of point-like particles falling radially onto black holes is also provided. Our results show that, when the central object is a black hole, the spectrum is far from having only one clear, monochromatic peak at the frequency of the fundamental quasi-normal mode. On the contrary, it shows a complex pattern, with distinctive interference fringes produced by the interaction between the infalling matter and the underlying perturbed spacetime, in close agreement with results for point-like particles. Remarkably, most of the energy is emitted at frequencies lower than that of the fundamental mode of the black hole. Similar results are obtained for extended shells accreting onto neutron stars, but in this case the contribution of the stellar fundamental mode stands clearly in the energy spectrum. Our analysis illustrates that the gravitational wave signal driven by accretion onto compact objects is influenced more by the details and dynamics of the process, and the external distribution of matter, than by the quasi-normal mode structure of the central object. The gravitational waveforms from such accretion events appear to be much more complex than former simplified assumptions predicted.

Nagar, Alessandro; Díaz, Guillermo; Pons, José A.; Font, José A.

2004-06-01

117

2H quadrupolar Carr-Purcell-Meiboom-Gill NMR for paramagnetic solids  

NASA Astrophysics Data System (ADS)

2H ( I = 1) quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) NMR methods in the presence of a paramagnetic shift interaction are reported. Pulse sequences based on quadrupole echo that can compensate effect of the shift interaction were adapted to obtain undistorted QCPMG spectra. The methods were demonstrated by 2H NMR measurement for paramagnetic CoSiF 6·6H 2O using strong radio-frequency pulses and by computer simulation. Detection of molecular dynamics by the present QCPMG method was also examined.

Iijima, Takahiro; Nishimura, Katsuyuki

2011-09-01

118

A Conduction Cooled High Temperature Superconductor Quadrupolar Superferric Magnet, Design and Construction  

NASA Astrophysics Data System (ADS)

The paper presents the prototype of an YBCO superferric quadrupolar magnet for high gradient magnetic field generation, design and construction. The temperature of the superconducting coil has to be kept within safe limits or the HTS would exit the superconductive state. Of particular concern is the "warm" beam tube that passes through the magnet. Cryogenic conduction cooling with a closed cycle G-M Cooler may ensure the removal of the ambient heat influx. Numerical simulation results on the magnetic field and heat transfer problems are then discussed. The computational domain is abstracted out of the CAD design of the system. The design solution is presented and compared with the numerical simulations results.

Dobrin, I.; Morega, A. M.; Nedelcu, A.; Morega, M.; Neamtu, J.

2014-05-01

119

Characterization of quantum algorithms by quantum process tomography using quadrupolar spins in solid-state nuclear magnetic resonance  

NASA Astrophysics Data System (ADS)

NMR quantum computing with qubit systems represented by nuclear spins (I=12) in small molecules in liquids has led to the most successful experimental quantum information processors so far. We use the quadrupolar spin-32 sodium nuclei of a NaNO3 single crystal as a virtual two-qubit system. The large quadrupolar coupling in comparison with the environmental interactions and the usage of strongly modulating pulses allow us to manipulate the system fast enough and at the same time keeping the decoherence reasonably slow. The experimental challenge is to characterize the ``calculation'' behavior of the quantum processor by process tomography which is here adapted to the quadrupolar spin system. The results of a selection of quantum gates and algorithms are presented as well as a detailed analysis of experimental results.

Kampermann, H.; Veeman, W. S.

2005-06-01

120

DFT 2H quadrupolar coupling constants of ruthenium complexes: a good probe of the coordination of hydrides in conjuction with experiments.  

PubMed

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

del Rosal, Iker; Gutmann, Torsten; Maron, Laurent; Jolibois, Franck; Chaudret, Bruno; Walaszek, Bernadeta; Limbach, Hans-Heinrich; Poteau, Romuald; Buntkowsky, Gerd

2009-07-21

121

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

SciTech Connect

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.

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

122

A Non-radial Eruption in a Quadrupolar Magnetic Configuration with a Coronal Null  

NASA Astrophysics Data System (ADS)

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 ~2 × 1031 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° 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.

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

2012-10-01

123

Extreme High Velocity Components in Quadrupolar Outflow of NGC 1333 IRAS 2A  

NASA Astrophysics Data System (ADS)

We have mapped a quadrupolar outflow of NGC 1333 IRAS 2A with the Submillimeter Array in CO (2-1) and SiO (5-4) at an angular resolution of 3". The quadrupolar outflow consists of an extended north-south outflow and a collimated east-west outflow. Our observations newly discovered extreme high velocity (EHV) components (? 20 km/s) within a north-south wide-angle cavity. These jet-like EHV components are detected near the YSO and outflow vertexes and imply a jet axis along the presumable cavity shell. On the other hand, the east-west outflow shows a bow-shock delineated by standard high velocity (? 20 km/s) CO emission and an off-axis EHV component in the west lobe. In the southern EHV component, two distinct kinematic features show an outflow overtaking process with an interface coincided with nearby shocked H2 emission. Considering shock dynamics of these EHV components, we witnessed an ongoing jet interaction with earlier ejected materials and surrounding envelop.

Tsai, Cheng-Hung; Chen, Vivien; Lee, Chin-Fei; Hirano, Naomi; Shang, Hsien

2013-07-01

124

Thermodynamic properties of mixtures of dipolar and quadrupolar hard spheres: Theory and simulation  

SciTech Connect

We report a comprehensive study of the thermodynamic properties (the Helmholtz energy, configurational energy, compressibility factor, and chemical potentials) for mixtures of dipolar hard spheres and quadrupolar hard spheres by computer simulation and from perturbation theory based on the Pade approximation. The dipole moment of dipolar component is fixed at {mu}{sub {ital A}}{sup *2}=3.0 and the quadrupole moment of quadrupolar component is varied up to {ital Q}{sub {ital B}}{sup *2}=3.0. The results show that the Pade approximation gives a good description of the Helmholtz energy and configuration energy of the mixtures, but some discrepancies are found for their derivatives, especially for compressibility factor. In view of very large deviations for the system from simple mixtures, the Pade approximation is rather successful for the system. These results are being used as a reference system in our effort to develop an equation of state for the CaCl{sub 2}--H{sub 2}O system.

Jiang, S.; Pitzer, K.S. [Department of Chemistry and Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)] [Department of Chemistry and Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)

1995-05-15

125

High-order Ho multipoles in HoB2C2 observed with soft resonant x-ray diffraction  

NASA Astrophysics Data System (ADS)

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 (00\\frac{1}{2}) component of the magnetic order exhibits a Brillouin type increase below the orbital ordering temperature TQ, 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 TQ.

Princep, A. J.; Mulders, A. M.; Schierle, E.; Weschke, E.; Hester, J.; Hutchison, W. D.; Tanaka, Y.; Terada, N.; Narumi, Y.; Nakamura, T.

2012-02-01

126

High-order Ho multipoles in HoB2C2 observed with soft resonant x-ray diffraction.  

PubMed

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

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

127

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

128

Quadrupolar effects in PrCu{sub 2}Si{sub 2}  

SciTech Connect

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.

Osborn, R. [Argonne National Lab., IL (United States); Goremychkin, E.A. [Rutherford Appleton Lab., Chilton (United Kingdom). ISIS Science Div.

1994-05-01

129

Magnetic-field-induced orientational phase structure transition.  

PubMed

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

Dou, Yingying; Dong, Shuli; Hao, Jingcheng

2014-02-11

130

Magnetic field induced properties of type II superconducting microstrip resonators  

NASA Astrophysics Data System (ADS)

The vortex effects of high temperature superconducting (HTS) microstrip resonators have been studied using the theoretical approach developed by Coffey and Clem (CC). A rectangular HTS strip resonator printed on sapphire substrate and subjected to a static magnetic field is considered, where the HTS strip is in the mixed state. An impedance type Green’s function is derived which connects the strip current to the electric field around the resonator, in the Fourier transformed domain. Galerkin’s procedure is used in the spectral domain to determine the resonant frequency and the unloaded Q value, both of which are computed for different applied fields, reduced temperatures and superconducting strip thicknesses. The results reveal considerable influence of applied field on resonant frequency and quality factor due to vortex motion, which should be considered when designing resonators which operate under external magnetic field.

Andrews, Jolly; Mathew, Vincent

2012-02-01

131

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

PubMed

A ferrofluid emulsion, subjected to a slowly increasing magnetic field, exhibits a complicated structural behavior: a gas of Brownian particles changes to columnar solid structures due to induced dipole interaction. Two transition (intermediate) structural regimes are observed: (i) randomly distributed chains and particles and (ii) distinct thin columns and randomly distributed chains and particles. Three structural transition magnetic fields are found, one marking each structural transition, from the initial to the final structural regime. A structural diagram of the structural transition magnetic fields, H(C), versus particle volume fractions, straight phi, is constructed experimentally. Theoretical models of scaling calculations, based upon the dominant magnetic interaction in each structural regime, give the three structural transition magnetic-field relations as H(C1) proportional to straight phi(-1/2), H(C2) proportional to straight phi(-1/4), and H(C3) proportional to (straight phi(gamma)/G2)exp(piG/straight phi((gamma/2))), where gamma=0.39 and G=0.29 for our sample. The final end shape of columns and the relative position between columns show that the end-end repulsion between chains is important in the structural formation. PMID:11304256

Ivey, M; Liu, J; Zhu, Y; Cutillas, S

2001-01-01

132

[Magnetic field induced structural changes of Oncorhynchus masou retina ].  

PubMed

The work describes the retinomotor response of Oncorhynchus masou young kept at illumination ranging from 1 to 10 lux, exposed to a field of a permanent magnet, and under conditions of geomagnetic field compensation. Retinomotor response in young exposed to magnetic field in darkness corresponds to partial light adaptation. During the exposure to a field of a permanent magnet the pigment was found to concentrate in pigmentocyte processes endings, forming the layer, that subdivided cone outer segments and rod outer segments and ellipsoids. Pigment in an aggregated state poorly shielded rod outer segments. In experiments with geomagnetic field compensation in darkness double and central cones were significantly elongated, the pigment is concentrated in initial parts of the processes and in pigmentocyte bodies. Pigment demonstrates the reaction that is similar to darkness adaptation, while the state of photoreceptors corresponds to a partial light adaptation. The changes of a natural magnetic field were accompanied by unusual retinomotor responses, in which the state of photoreceptors and retinal pigment epithelium did not correspond to photopic, mesopic or scotopic adaptation. PMID:15232871

Zagal'skaia, E O; Gniubkina, V P; Maksimovich, A A

2004-01-01

133

Static Magnetic Field Induced Stochastic Resonance in Gene Expression  

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

134

Magnetic field induced differential neutron phase contrast imaging  

SciTech Connect

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

Strobl, M.; Treimer, W.; Walter, P.; Keil, S.; Manke, I. [Department of Physical Chemistry, Ruprecht Karls University Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany and Hahn-Meitner Institute Berlin, SF1, Glienickerstr. 100, 14109 Berlin (Germany); Hahn-Meitner Institute Berlin, Glienickerstr. 100, 14109 Berlin, Germany and University of Applied Sciences (TFH) Berlin, Luxemburger Str. 10, 13353 Berlin (Germany); Hahn-Meitner Institute Berlin, Glienickerstr. 100, 14109 Berlin (Germany)

2007-12-17

135

Magnetic-field induced screening effect and collective excitations  

SciTech Connect

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.

Fukushima, Kenji [Department of Physics, Keio University, Kanagawa 223-8522 (Japan)

2011-06-01

136

Proposal for a magnetic field induced graphene dot  

Microsoft Academic Search

Quantum dots induced by a strong magnetic field applied to a single layer of graphene in the perpendicular direction are investigated. The dot is defined by a model potential which consists of a well of depth DeltaV relative to a flat asymptotic part and quantum states formed from the zeroth Landau level are considered. The energy of the dot states

P. A. Maksym; M. Roy; M. F. Craciun; S. Russo; M. Yamamoto; S. Tarucha; H. Aoki

2010-01-01

137

Proposal for a magnetic field induced graphene dot  

NASA Astrophysics Data System (ADS)

Quantum dots induced by a strong magnetic field applied to a single layer of graphene in the perpendicular direction are investigated. The dot is defined by a model potential which consists of a well of depth ?V relative to a flat asymptotic part and quantum states formed from the zeroth Landau level are considered. The energy of the dot states cannot be lower than -?V relative to the asymptotic potential. Consequently, when ?V is chosen to be about half of the gap between the zeroth and first Landau levels, the dot states are isolated energetically in the gap between Landau level 0 and Landau level -1. This is confirmed with numerical calculations of the magnetic field dependent energy spectrum and the quantum states. Remarkably, an antidot formed by reversing the sign of ?V also confines electrons but in the energy region between Landau level 0 and Landau level +1. This unusual behaviour gives an unambiguous signal of the novel physics of graphene quantum dots.

Maksym, P. A.; Roy, M.; Craciun, M. F.; Russo, S.; Yamamoto, M.; Tarucha, S.; Aoki, H.

2010-09-01

138

Magnetic field induced lattice ground states from holography  

NASA Astrophysics Data System (ADS)

We study the holographic field theory dual of a probe SU(2) Yang-Mills field in a background (4 + 1)-dimensional asymptotically Anti-de Sitter space. We find a new ground state when a magnetic component of the gauge field is larger than a critical value. The ground state forms a triangular Abrikosov lattice in the spatial directions perpendicular to the magnetic field. The lattice is composed of superconducting vortices induced by the condensation of a charged vector operator. We perform this calculation both at finite temperature and at zero temperature with a hard wall cutoff dual to a confining gauge theory. The study of this state may be of relevance to both holographic condensed matter models as well as to heavy ion physics. The results shown here provide support for the proposal that such a ground state may be found in the QCD vacuum when a large magnetic field is present.

Bu, Yan-Yan; Erdmenger, Johanna; Shock, Jonathan P.; Strydom, Migael

2013-03-01

139

Magnetic Field Induced Microwave Absorption in High-Temperature Superconductors  

NASA Astrophysics Data System (ADS)

The non-resonant microwave absorption technique is used to probe the electrodynamic behavior of the high temperature superconductors (HTSC) below the critical transition temperature. Flux quantization is studied in single crystal samples of rm Y_1Ba_2Cu_3O _{7-gamma} (YBCO) as a function of externally applied dc magnetic field at constant amplitude of the microwave magnetic field, and as a function of the microwave field amplitude at nominally zero dc field. Periodic oscillations in the modulated microwave absorption (MA) due to flux quantization are observed in both scans. In the microwave scan, only a single junction is activated in the temperature range 0.1 < t <= 0.9, where t = T/T_{ rm c} is the reduced temperature. Measurements of flux quantization are discussed in the context of a model describing the quantum transitions of a weakly connected superconducting ring. From the temperature dependence of the microwave scan spectra, the superconducting penetration depth lambda_{rm L} is shown to obey the empirical two-fluid model lambda_{L}(T)/lambda _{L}(0) = (1-t^4)^{ -1/2} in the temperature range critical current is found to have the temperature dependence given by rm J_{c}(T)/J_{c} (0) = rm (1-t)^{1.9+/- 0.2 } in the same temperature range and suggests a superconductor-normal-superconductor (SNS) junction. The microwave absorption has been studied directly as a function of temperature (DA) and applied magnetic field (FDA) at a given temperature for ceramic samples of YBCO and rm Bi_{1.65}Pb _{0.35}Sr_2Ca_2Cu_3O _{9.8} (BP2223). The temperature dependence of the FDA signals in the temperature regime near T_{rm c} (t > 0.8) is explained in terms of a thermally activated flux flow model. Values of 9.3 and 23 meV were obtained for the activation energy for the YBCO and BP2223 samples, respectively. The correspondence between the information obtained from the MA and the FDA signals is discussed. Results of a thermally modulated absorption (THMA) measurement are compared to the numerically computed temperature derivative of the DA curve. The FDA upon first exposure to field (virgin curve) is studied for ceramic samples of YBCO. A simple model based on resistively shunted Josephson junctions is shown to qualitatively account for almost all of the observations for the low-field dependent absorption signals. It is found that the junctions responsible for the field dependent absorption signals are superconductor -insulator-superconductor (SIS) junctions.

Kish, Kevin Francis Patrick

140

Strong Magnetic Field Induced Changes of Gene Expression in Arabidopsis  

NASA Astrophysics Data System (ADS)

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

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

2005-07-01

141

Coexistence of ferro- and antiferromagnetic order in Mn-doped Ni$_2$MnGa  

Microsoft Academic Search

Ni-Mn-Ga is interesting as a prototype of a magnetic shape-memory alloy\\u000ashowing large magnetic field induced strains. We present here results for the\\u000amagnetic ordering of Mn-rich Ni-Mn-Ga alloys based on both experiments and\\u000atheory. Experimental trends for the composition dependence of the magnetization\\u000aare measured by a vibrating sample magnetometer (VSM) in magnetic fields of up\\u000ato several tesla

J. Enkovaara; O. Heczko; A. Ayuela; R. M. Nieminen

2002-01-01

142

Relation between electric phase and magnetic ordering of Y-type Hexaferrite  

NASA Astrophysics Data System (ADS)

Y-type hexaferrite Ba0.5Sr1.5Zn2Fe12O22(BSZFO), one of multiferroic materials, we could acquire magnetic field-induced commensurate phase, changing of magnetic phase of BSZFO and Ba0.5Sr1.5Zn2(Fe1-xAlx)12O22 (x = 0.08)(BSZFAO) using resonant soft X-ray scattering(RSXS) experiment. Also we could confirm that magnetic ordering changing has some relation with electric phase transition, q=1.5 at ferroelectric phase not only BSZFO but also BSZFAO. This research results were acquired by using 2A EPU beamline at PAL.

Noh, Woo-Suk; Jang, H.; Ko, K.-T.; Park, J.-H.; Chun, S. H.; Kim, K. H.; Park, B.-G.; Kim, J.-Y.

2011-03-01

143

Superfluid density and competing orders in d-wave superconductors  

NASA Astrophysics Data System (ADS)

We derive expressions for the superfluid density ?s in the low-temperature limit T ->0 in d-wave superconductors, taking into account the presence of competing orders such as spin-density waves, is-pairing, etc. Recent experimental data for the thermal conductivity and for elastic neutron scattering in La2-xSrxCuO4 suggest there are magnetic field induced anomalies that can be interpreted in terms of competing orders. We consider the implications of these results for the superfluid density and show in the case of competing spin-density wave order the usual Volovik-like ?H depletion of ?s(H) is replaced by a slower dependence of ?s on the applied magnetic field H. We show that it is crucial to include the competing order parameter in the self-consistent equation for the impurity scattering rate.

Sharapov, Sergei; Carbotte, Jules

2006-03-01

144

Superfluid density and competing orders in d -wave superconductors  

NASA Astrophysics Data System (ADS)

We derive expressions for the superfluid density ?s in the low-temperature limit T?0 in d -wave superconductors, taking into account the presence of competing orders such as spin-density waves, idxy pairing, etc. Recent experimental data for the thermal conductivity and for elastic neutron scattering in La2-xSrxCuO4 suggest there are magnetic field induced anomalies that can be interpreted in terms of competing orders. We consider the implications of these results for the superfluid density and show in the case of competing spin-density wave order that the usual Volovik-like H depletion of ?s(H) is replaced by a slower dependence on applied magnetic field. We find that it is crucial to include the competing order parameter in the self-consistent equation for the impurity scattering rate.

Sharapov, S. G.; Carbotte, J. P.

2006-03-01

145

Resolution enhancement in 1D solid-state NMR spectra of spin-9\\/2 quadrupolar nuclei  

Microsoft Academic Search

NMR is an insensitive spectroscopy, which often requires numerous accumulations, especially for 2D high-resolution methods (MQMAS and STMAS) for quadrupolar nuclei in solids. This may be a very important limitation for the case of insensitive nuclei, where a 1D spectrum with better resolution than the central-transition is then highly desirable. This problem has been addressed for the case of spin-5\\/2

Jean-Paul Amoureux; Julien Trébosc

2006-01-01

146

Low temperature solid-state NMR experiments of half-integer quadrupolar nuclides: caveats and data analysis  

Microsoft Academic Search

Solid-state NMR spectroscopy of half-integer quadrupolar nuclides has received a lot of interest recently with the advent of new methodologies and higher magnetic fields. We present here the extension of our previous low temperature method to an 18.8T system. This new probe entailed a total redesign including a cross coil and variable capacitors that are operational at cryogenic temperatures. The

Andrew S. Lipton; Robert W. Heck; Jesse A. Sears; Paul D. Ellis

2004-01-01

147

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

PubMed

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

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

2000-12-01

148

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

PubMed

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

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

2005-11-30

149

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

NASA Astrophysics Data System (ADS)

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

Filippov, Boris; Koutchmy, Serge; Tavabi, Ehsan

2013-08-01

150

Influence of sodium ion dynamics on the 23Na quadrupolar interaction in sodalite: a high-temperature 23Na MAS NMR study.  

PubMed

High-temperature 33Na MAS NMR experiments up to 873 K for a number of different sodalites (Na8[AlSiO4]6(NO3)2, Na8[AlSiO4]6(NO2)2, Na8[AlSiO4]6I2, Na7.9[AlSiO4]6(SCN)7.9 x 0.5H2O, Na8[AlGeO4]6(NO3)2, and Na7[AlSiO4]6(H3O2) x 4H2O) were carried out. The spectra of the first five sodalites consist of a quadrupolar MAS pattern with different quadrupolar coupling constants. The quadrupolar interaction for the thiocyanate sodalite, the nitrate aluminosilicate, and germanate sodalite decreases strongly passing a coalescence state on heating, while the quadrupolar interaction of the iodide and nitrite sample shows nearly no change. The basic hydrosodalite shows an asymmetric lineshape at room temperature and, between 350 and 370 K, a second line due to the evaporation of cage-water emerges. The linewidth increases with rising temperature. The temperature dependence of the quadrupolar interaction seems to be a function of the sodalite beta-cage expansion. Two conceivable jump mechanisms are proposed for a tetrahedral two-site jump between occupied and unoccupied tetrahedral sites. PMID:11270743

Fechtelkord, M

2000-01-01

151

Anisotropy of the solvent self-diffusion tensor as a probe of nematic ordering within dispersions of nanocomposites.  

PubMed

The anisotropy of the solvent self-diffusion coefficient within suspensions of nanoparticles is measured by (1)H nuclear magnetic resonance with pulsed field gradient and used as a new procedure to detect nematic ordering. The potentiality of this method is illustrated using aqueous clay dispersions whose nematic ordering was already detected by (23)Na quadrupolar splitting. PMID:11690516

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

2001-11-12

152

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

PubMed

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

Dib, Eddy; Alonso, Bruno; Mineva, Tzonka

2014-05-15

153

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

Microsoft Academic Search

Owing to the implementation of acquisition techniques specific for nuclei with very large quadrupolar interaction (full shifted echo and variable offset cumulative spectra (VOCS)), NMR spectra of 69Ga and 71Ga are obtained in crystallised (PbGaF5, Pb3Ga2F12, Pb9Ga2F24 and CsZnGaF6) and glassy (PbF2–ZnF2–GaF3) gallium fluorides. Simulations of both static (full echo or VOCS) and 15 kHz MAS spectra allow to obtain

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

1999-01-01

154

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

NASA Astrophysics Data System (ADS)

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.

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

2010-04-01

155

Application of static microcoils and WURST pulses for solid-state ultra-wideline NMR spectroscopy of quadrupolar nuclei  

NASA Astrophysics Data System (ADS)

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).

Tang, Joel A.; O'Dell, Luke A.; Aguiar, Pedro M.; Lucier, Bryan E. G.; Sakellariou, Dimitris; Schurko, Robert W.

2008-12-01

156

Transmission of order in some unusual dilute systems  

NASA Technical Reports Server (NTRS)

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.

Adler, Joan; Palmer, R. G.; Meyer, H.

1987-01-01

157

Through-space R 3-HETCOR experiments between spin-1/2 and half-integer quadrupolar nuclei in solid-state NMR  

NASA Astrophysics Data System (ADS)

We present several new methods that allow to obtain through-space 2D HETCOR spectra between spin-1/2 and half-integer quadrupolar nuclei in the solid state. These methods use the rotary-resonance concept to create hetero-nuclear coherences through the dipolar interaction instead of scalar coupling into the HMQC and refocused INEPT experiments for spin n/2 ( n > 1). In opposite to those based on the cross-polarization transfer to quadrupolar nuclei, the methods are very robust and easy to set-up.

Trebosc, J.; Hu, B.; Amoureux, J. P.; Gan, Z.

2007-06-01

158

Symmetry-Amplified J Splittings for Quadrupolar Spin Pairs: A Solid-State NMR Probe of Homoatomic Covalent Bonds  

PubMed Central

Chemically informative J couplings between pairs of quadrupolar nuclei in dimetallic and dimetalloid coordination motifs are measured using J-resolved solid-state NMR experiments. It is shown that the application of a double-quantum filter is necessary to observe the J splittings and that, under these conditions, only a simple doublet is expected. Interestingly, the splitting is amplified if the spins are magnetically equivalent, making it possible to measure highly precise J couplings and unambiguously probe the symmetry of the molecule. This is demonstrated experimentally by chemically breaking the symmetry about a pair of boron spins by reaction with an N-heterocyclic carbene to form a ?-borylation reagent. The results show that the J coupling is a sensitive probe of bonding in diboron compounds and that the J values quantify the weakening of the B–B bond which occurs when forming an sp2–sp3 diboron compound, which is relevant to their reactivity. Due to the prevalence of quadrupolar nuclei among transition metals, this work also provides a new approach to probe metal–metal bonding; results for Mn2(CO)10 are provided as an example.

2013-01-01

159

From bipolar to quadrupolar electrode structures: an application of bond-detach lithography for dielectrophoretic particle assembly.  

PubMed

We describe a new, simple process for fabricating transparent quadrupolar electrode arrays enabling large-scale particle assembly by means of dielectrophoresis. In the first step, interdigitated electrode arrays are made by chemical wet etching of indium tin oxide (ITO). Then, the transition from a bipolar to a quadrupolar electrode arrangement is obtained by covering the electrode surface with a thin poly(dimethylsiloxane) (PDMS) film acting as an electrical insulation layer in which selective openings are formed using bond-detach lithography. The PDMS insulating layer thickness was optimized and controlled by adjusting experimental parameters such as the PDMS viscosity (modulated by the addition of heptane) and the PDMS spin-coating velocity. The insulating character of the PDMS membrane was successfully demonstrated by performing a dielectrophoretic assembly of polystyrene particles using interdigitated electrodes with and without a PDMS layer. The results show that the patterned PDMS film functions properly as an electrical insulation layer and allows the reconfiguration of the electric field cartography. Electric field simulations were performed in both configurations to predict the dielectrophoretic behavior of the particles. The simulation results are in perfect agreement with experiments, in which we demonstrated the formation of concentrated clusters of polystyrene particles and living cells of regular size and shape. PMID:24758738

Menad, Samia; El-Gaddar, Amal; Haddour, Naoufel; Toru, Sylvain; Brun, Mathieu; Buret, François; Frenea-Robin, Marie

2014-05-20

160

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

NASA Astrophysics Data System (ADS)

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 t2 domain with either of 1Q, two-spin 2Q or single-spin multiple-quantum coherence-evolutions in the indirect (t1) dimension. We employ experimental 23Na and 27Al NMR on sodium sulfite and the natural mineral sillimanite (SiAl2O5), 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.

Edén, Mattias

2010-05-01

161

Effect of strongly coupled plasma on the magnetic dipolar and quadrupolar transitions of two-electron ions  

NASA Astrophysics Data System (ADS)

Effect of strongly coupled plasma on the excitation energies and transition probabilities for the respective transitions 1s2:1Se --> 1sns:3Se (n = 2, 3, 4) and 1s2:1Se --> 1snp:3Po (n = 2, 3, 4) allowed by magnetic dipolar and quadrupolar excitations have been analyzed for the first time for the two-electron ions C4+, O6+, Ne8+, Mg10+, Si12+, and S14+. Time dependent Hatree-Fock theory within variational approach has been adopted for such a study. The effect of surrounding plasma has been treated through the standard Ion-Sphere (IS) model of the plasma where the plasma density is varied systematically from a low value to a pretty high value such that the respective excited states go over to continuum due to such a confinement. The effect of external pressure generated due to plasma confinement on the estimated spectral properties has been analyzed systematically.

Saha, Jayanta K.; Mukherjee, T. K.; Mukherjee, P. K.; Fricke, B.

2013-04-01

162

Efficient symmetry-based homonuclear dipolar recoupling of quadrupolar spins: double-quantum NMR correlations in amorphous solids.  

PubMed

We report novel symmetry-based pulse sequences for exciting double-quantum (2Q) coherences between the central transitions of half-integer spin quadrupolar nuclei in the NMR of rotating solids. Compared to previous 2Q-recoupling techniques, numerical simulations and 23Na and 27Al NMR experiments on Na2SO4 and the open-framework aluminophosphate AlPO-CJ19 verify that the new dipolar recoupling schemes display higher robustness to both radio-frequency field inhomogeneity and to spreads in resonance frequencies. These advances allowed for the first demonstration of 2Q-recoupling in an amorphous solid for revealing its intermediate-range structural features, in the context of mapping 27Al-27Al connectivities between the aluminium polyhedra (AlO4, AlO5 and AlO6) of a lanthanum aluminate glass (La0.18Al0.82O1.5). PMID:18989475

Lo, Andy Y H; Edén, Mattias

2008-11-28

163

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

NASA Astrophysics Data System (ADS)

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.

Schulz, M.

2008-05-01

164

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

SciTech Connect

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

Hubbard, S.F.; Petschek, R.G.; Singer, K.D. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics] [and others

1997-10-01

165

Observation of proximities between spin-1/2 and quadrupolar nuclei: Which heteronuclear dipolar recoupling method is preferable?  

SciTech Connect

We have recently shown that the dipolar-mediated heteronuclear multiple-quantum coherence (D-HMQC) method allows observing through-space proximities between spin-1/2 ({sup 1}H, {sup 13}C, {sup 31}P Horizontal-Ellipsis ) and quadrupolar ({sup 23}Na, {sup 27}Al Horizontal-Ellipsis ) nuclei. However, the D-HMQC effectiveness depends on the choice of the heteronuclear dipolar recoupling sequence. Here, we compare the efficiency and the robustness of four rotor-synchronized sequences: the symmetry-based ones, R4{sub 1}{sup 2}R4{sub 1}{sup -2} and its super-cycled version, SR4{sub 1}{sup 2}, and two schemes based on simultaneous amplitude and frequency modulations, denoted SFAM-1 and SFAM-2. For the SFAM methods, we point out efficient recoupling conditions that facilitate their experimental optimization and we introduce analytical expressions for the buildup of D-HMQC signal in the case of an isolated spin pair. We show that the main differences between these four sequences lie in the number of adjustable parameters and in their robustness with respect to chemical shift and homonuclear dipolar interactions. The relative performances of these four recoupling sequences are analyzed using average Hamiltonian theory, numerical simulations, and {sup 27}Al-{l_brace}{sup 31}P{r_brace} D-HMQC experiments on crystalline aluminophosphate.

Lu, X.; Lafon, O.; Trebosc, J.; Tricot, G.; Delevoye, L.; Mear, F.; Montagne, L.; Amoureux, J. P. [UCCS (CNRS-8181), Lille North of France University, Villeneuve d'Ascq 59652 (France)

2012-10-14

166

Effect of strongly coupled plasma on the magnetic dipolar and quadrupolar transitions of two-electron ions  

SciTech Connect

Effect of strongly coupled plasma on the excitation energies and transition probabilities for the respective transitions 1s{sup 2}:{sup 1}S{sup e}{yields} 1sns:{sup 3}S{sup e} (n = 2, 3, 4) and 1s{sup 2}:{sup 1}S{sup e}{yields} 1snp:{sup 3}P{sup o} (n = 2, 3, 4) allowed by magnetic dipolar and quadrupolar excitations have been analyzed for the first time for the two-electron ions C{sup 4+}, O{sup 6+}, Ne{sup 8+}, Mg{sup 10+}, Si{sup 12+}, and S{sup 14+}. Time dependent Hatree-Fock theory within variational approach has been adopted for such a study. The effect of surrounding plasma has been treated through the standard Ion-Sphere (IS) model of the plasma where the plasma density is varied systematically from a low value to a pretty high value such that the respective excited states go over to continuum due to such a confinement. The effect of external pressure generated due to plasma confinement on the estimated spectral properties has been analyzed systematically.

Saha, Jayanta K.; Mukherjee, T. K. [Department of Physics, Narula Institute of Technology, Agarpara, Kolkata 700 109, West Bengal (India); Mukherjee, P. K. [Department of Physics, Ramakrishna Mission Vivekananda University, Belur Math, Howrah 711202, West Bengal (India); Department of Mathematics, Visva Bharati, Santiniketan 731235, West Bengal (India); Fricke, B. [Institute fur Physik, Universitat Kassel, 34109 Kassel (Germany)

2013-04-15

167

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

SciTech Connect

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.

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

168

Pulse FT NMR of non-equilibrium states of half-integer spin quadrupolar nuclei in single crystals.  

PubMed

For quadrupolar nuclei with spin quantum numbers equal to 3/2, 5/2 and 7/2, the intensities of the NMR transitions in a single crystal are examined as a function of the rf excitation flip angle. Single-quantum NMR intensities are calculated using density matrix theory beginning under various non-equilibrium conditions and are compared with those determined experimentally. As a representative spin-3/2 system, the flip-angle dependence of the (23)Na NMR intensities of a single crystal of NaNO(3) was investigated beginning with the inversion of the populations associated with one of the satellite transitions. Subsequently, the populations of both satellite transitions were inverted using highly frequency-selective hyperbolic secant pulses. Calculated and experimental intensities are in good agreement. As an example of a spin-5/2 system, the flip-angle dependence of the (27)Al NMR transition intensities was determined using a single crystal of sapphire, Al(2)O(3), starting under different nuclear spin population conditions. The experimental trends mimicked those predicted by the density matrix calculations but the agreement was not as good as for the spin-3/2 case. Some SIMPSON simulations were also carried out to confirm the results generated by our density matrix calculations. The theoretical flip-angle behavior of the NMR transition intensities obtained from a spin-7/2 spin system is also discussed. PMID:19962334

Nakashima, Thomas T; Harris, Kristopher J; Wasylishen, Roderick E

2010-02-01

169

Deuterium nuclear magnetic resonance of specifically labeled native collagen. Investigation of protein molecular dynamics using the quadrupolar echo technique.  

PubMed Central

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.

Jelinski, L W; Sullivan, C E; Batchelder, L S; Torchia, D A

1980-01-01

170

Examples of Hartmann-Hahn match conditions for CP/MAS between two half-integer quadrupolar nuclei.  

PubMed

Hartmann-Hahn match conditions for n2 --> M2 CP/MAS between two quadrupolar nuclei, spin-lock signal as a function of effective nutation frequency, and the correlation of effective nutation frequency and radiofrequency field strength are reported for three samples: sodium diborate (Na2B4O7), aluminum boride (AlB2), and lithiump aluminate (LiAlO2). Radiofrequency field strengths used for CP/MAS are both greater and less than the sample spinning speed of 10 kHz, resulting in the observation of both zero-quantum and double-quantum matches, which have signals of opposite sign. The match conditions for Na2B4O7 are as expected from published theory and CP/MAS experiments on spins 12 and n2 (n = 3 or 5) with quadrupole frequencies (omegaQ) large compared to the radiofrequency field strength of the CP contact pulse, consisting mainly of sideband matches at one and two times the sample spinning frequency, and the correlation of effective nutation frequency and radiofrequency field strength supports the conclusion that omegaQ is large for both 11B and 23Na. Aluminum-27 in AlB2 may have either small or intermediate omegaQ, and 7Li in LiAlO2 is proposed to have intermediate omegaQ in relation to the radiofrequency field strength, and both have curves of the spin-lock signal as a function of effective nutation frequency with central minima, differing from those of the nuclei with large omegaQ. The sign of the CP/MAS signal for AlB2 and LiAlO2 appears to vary with the CP field strengths for the two nuclei so that positive or negative signals cannot be consistently correlated with zero- or double-quantum matches. However, it is possible to assign at least some of the matches as close to integral multiples of the sample spinning frequency, and some of these are matches at greater than two times the sample spinning frequency. PMID:10388589

Eastman, M A

1999-07-01

171

Examples of Hartmann-Hahn Match Conditions for CP/MAS between Two Half-Integer Quadrupolar Nuclei  

NASA Astrophysics Data System (ADS)

Hartmann-Hahn match conditions for {n}/{2} ? {M}/{2} CP/MAS between two quadrupolar nuclei, spin-lock signal as a function of effective nutation frequency, and the correlation of effective nutation frequency and radiofrequency field strength are reported for three samples: sodium diborate (Na 2B 4O 7), aluminum boride (AlB 2), and lithium aluminate (LiAlO 2). Radiofrequency field strengths used for CP/MAS are both greater and less than the sample spinning speed of 10 kHz, resulting in the observation of both zero-quantum and double-quantum matches, which have signals of opposite sign. The match conditions for Na 2B 4O 7 are as expected from published theory and CP/MAS experiments on spins {1}/{2} and {n}/{2} ( n = 3 or 5) with quadrupole frequencies (? Q) large compared to the radiofrequency field strength of the CP contact pulse, consisting mainly of sideband matches at one and two times the sample spinning frequency, and the correlation of effective nutation frequency and radiofrequency field strength supports the conclusion that ? Q is large for both 11B and 23Na. Aluminum-27 in AlB 2 may have either small or intermediate ? Q, and 7Li in LiAlO 2 is proposed to have intermediate ? Q in relation to the radiofrequency field strength, and both have curves of the spin-lock signal as a function of effective nutation frequency with central minima, differing from those of the nuclei with large ? Q. The sign of the CP/MAS signal for AlB 2 and LiAlO 2 appears to vary with the CP field strengths for the two nuclei so that positive or negative signals cannot be consistently correlated with zero- or double-quantum matches. However, it is possible to assign at least some of the matches as close to integral multiples of the sample spinning frequency, and some of these are matches at greater than two times the sample spinning frequency.

Eastman, Margaret A.

1999-07-01

172

Dephasing and relaxation of central hole spins by nuclear spin baths in InGaAs quantum dots: role of nuclear quadrupolar coupling  

NASA Astrophysics Data System (ADS)

Single electron or hole spins in III-V semiconductor quantum dots (QDs) are promising candidates for solid-state qubits. Their coherence properties are typically governed by the hyperfine coupling between these ``central'' electronic spins and the dense surrounding bath of lattice nuclear spins. Theoretically this is a challenging problem due to its many-body and strongly-correlated nature. Here we measure the spin dynamics of holes in InGaAs quantum dots by detecting their intrinsic, random spin fluctuations while in thermal equilibrium, which reveals the spin correlation time scales ?h and the functional form of bath-induced spin relaxation. In zero magnetic field, ?h is very long (˜400 ns) and decays exponentially, in marked contrast with recent theories. ?h increases to ˜5 ?s in small (100 G) longitudinal fields, and the spin dynamics evolve to a very slow ˜1/ln(t) decay [1]. We model the influence of nuclear quadrupolar coupling on spin dynamics in these strained QDs for both electrons and holes [2], and find a good agreement with experimental data when the quadrupolar coupling exceeds the hyperfine coupling strength. [1] Yan Li, N. Sinitsyn, et al., PRL 108, 186603 (2012). [2] N. Sinitsyn, Yan Li, et al., PRL 109, 166605 (2012).

Li, Yan; Sinitsyn, N. A.; Saxena, A.; Smith, D. L.; Reuter, D.; Wieck, A. D.; Yakovlev, D. R.; Manfred, B.; Crooker, S. A.

2013-03-01

173

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

PubMed

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

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

2011-09-01

174

Superconductivity and the high-field ordered phase in the heavy-fermion compound PrOs4Sb12  

NASA Astrophysics Data System (ADS)

Superconductivity is observed in the filled skutterudite compound PrOs4Sb12 below a critical temperature Tc = 1.85 K and appears to develop out of a nonmagnetic heavy Fermi liquid with an effective mass mlowast approx 50 m e, where me is the free electron mass. Features associated with a cubic crystalline electric field are present in magnetic susceptibility, specific heat, electrical resistivity, and inelastic neutron scattering measurements, yielding a Pr3+ energy level scheme consisting of a Gamma3 nonmagnetic doublet ground state, a low-lying Gamma5 triplet excited state at ~10 K, and Gamma4 triplet and Gamma1 singlet excited states at much higher temperatures. Measurements also indicate that the superconducting state is unconventional and consists of two distinct superconducting phases. At high fields and low temperatures, an ordered phase of magnetic or quadrupolar origin is observed, suggesting that the superconductivity may occur in the vicinity of a magnetic or quadrupolar quantum critical point.

Maple, M. B.; Ho, P.-C.; Frederick, N. A.; Zapf, V. S.; Yuhasz, W. M.; Bauer, E. D.; Christianson, A. D.; Lacerda, A. H.

2003-07-01

175

One- and two-pulse quadrupolar excitation schemes of the ion motion in a Penning trap investigated with FT-ICR detection  

NASA Astrophysics Data System (ADS)

In a Penning ion trap the interconversion between the radial motional modes of stored particles can be accomplished by applying one- and two-pulse (Ramsey) azimuthal quadrupolar radio frequency fields. In this work the interaction of ions with the excitation fields has been probed by Fourier transform ion cyclotron resonance (FT-ICR) detection. A theoretical description of this interaction is derived by use of a quasi-classical coherent state and the interconversion of modes is interpreted in a quantum-mechanical context. The dipolar-detection FT-ICR signal at the modified cyclotron frequency has been studied as a function of the interaction parameters such as excitation frequency, amplitude and duration and is compared with the theoretical results.

Heck, M.; Blaum, K.; Cakirli, R. B.; Kretzschmar, M.; Marx, G.; Rodríguez, D.; Schweikhard, L.; Stahl, S.; Ubieto-Díaz, M.

2012-06-01

176

Topology of magnetic-field induced electron current density in the cubane molecule  

NASA Astrophysics Data System (ADS)

A spatial model of the electronic current density induced in the cubane molecule by applying an external magnetic-field has been constructed employing quantum mechanical methods at the Hartree-Fock level of accuracy. The topological features of the current density vector field are described via a stagnation graph that shows the isolated points and the lines at which the current vanishes. Shielding density maps based on the differential Biot-Savart law, along with a collection of current density maps, explain magnetic shielding at hydrogen and carbon nuclei, and virtual shielding at ring and cage centers.

Pelloni, Stefano; Lazzeretti, Paolo

2008-05-01

177

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

PubMed Central

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.

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

2014-01-01

178

Magnetic-Field-Induced Crossover to a Nonuniversal Regime in a Kondo Dot  

Microsoft Academic Search

We have measured the magnetic splitting DeltaK of a Kondo peak in the differential conductance of a single-electron transistor while tuning the Kondo temperature TK along two different paths in parameter space: varying the dot-lead coupling at a constant dot energy and vice versa. At a high magnetic field B, the changes of DeltaK with TK along the two paths

Tai-Min Liu; Bryan Hemingway; Andrei Kogan; Steven Herbert; Michael Melloch

2009-01-01

179

A magnetic field-induced crossover to a non-universal regime in a Kondo dot  

Microsoft Academic Search

We have measured the magnetic splitting, deltaK, of a Kondo peak in the differential conductance of a Single-Electron Transistor while tuning the Kondo temperature, TK, along two different paths in the parameter space: varying the dot-lead coupling at a constant dot energy, and vice versa. At a high magnetic field, B, the changes of deltaK with TK along the two

Andrei Kogan; Tai-Min Liu; Bryan Hemingway; Steven Herbert; Michael Melloch

2009-01-01

180

External magnetic field-induced selective biodistribution of magnetoliposomes in mice  

PubMed Central

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

2012-01-01

181

Effective magnetic fields induced by EIT in ultra-cold atomic gases  

Microsoft Academic Search

We study the influence of two resonant laser beams (to be referred to as the control and probe beams) on the centre-of-mass motion of ultra-cold atoms characterized by three energy levels of the Lambda-type. The laser beams being in the electromagnetically induced transparency (EIT) configuration drive the atoms to their dark states. We impose the adiabatic approximation and obtain an

G. Juzeliunas; J. Ruseckas; P. Öhberg

2005-01-01

182

Magnetic-field-induced crystallographic texture enhancement in cold-deformed FePt nanostructured magnets  

Microsoft Academic Search

This paper reports a unique approach to the fabrication of magnetically anisotropic nanostructured FePt magnets: cyclic sheath cold rolling and subsequent magnetic annealing. High magnetic fields enhance both crystallographic texture and magnetic properties of cold-deformed FePt nanostructured magnets. Magnetic annealing increases (001) out-of-plane texture of the FePt hard phase by 50% and introduces magnetic anisotropy in the annealed samples. It

B. Z. Cui; K. Han; D. S. Li; H. Garmestani; J. P. Liu; N. M. Dempsey; H. J. Schneider-Muntau

2006-01-01

183

A direct evidence of magnetic field induced lateral transport of fast electrons  

NASA Astrophysics Data System (ADS)

Fast electrons generated in the interaction of intense ultrashort laser pulses with solid targets have important roles in both fundamental physics and in technological application such as fast ignition fusion. A fast electron beam propagating into the cold target excites strong self-generated electric and magnetic fields, which in turn govern the transport of the beam itself. These strong fields can deviate the fast electrons propagating into the target and can confine them along the target surface. We observe an ultrafast surface ionization wave from the reflectivity signal driven by the interaction of 3x10^17 W cm-2 intense pulse with a glass target. The reflectivity signal is found to expand three times the initially photoexcited volume, driven by the lateral transport of fast electrons. A simultaneous measurement of the evolution of the generated megagauss magnetic field reveals the direct role of anomalous resistivity in governing the transport of the fast electrons. The similarity in the spatial extent of reflectivity and magnetic field signals indicate that the surface transport is induced by the magnetic field. The lateral transport of fast electrons is explained using a model of magnetic field diffusion.

Singh, Prashant Kumar; Chatterjee, Gourab; Adak, Amitava; Lad, Amit D.; Ahmed, Saima; Gattamraju, Ravindra Kumar

2012-10-01

184

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

PubMed

We 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. We 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 microT. 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 microV/m. The addition of either 51.1 or 78.4 microT 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 our 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. These results together with those reported previously point to two distinct physiological effects produced in regenerating planaria by exposure to weak extremely-low-frequency (ELF) magnetic fields. They further suggest that the planarian, which has recently been identified elsewhere as an excellent system for use in teratogenic investigations involving chemical teratogens, might be used similarly in teratogenic investigations involving ELF magnetic fields. PMID:8986364

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

1996-01-01

185

The Magnetic Field Induced by the Solar Wind on the Dayside of Mars  

Microsoft Academic Search

The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument on Mars Express can be used to measure the local magnetic field. The technique relies on the detection of the electron echoes. These are series of echoes that are equally spaced in time at the electron cyclotron period. The echoes are believed to be caused by the periodic return

F. Akalin; D. A. Gurnett; T. F. Averkamp; D. L. Kirchner; M. H. Acuna; J. E. Connerney; N. F. Ness; J. J. Plaut; G. Picardi

2007-01-01

186

Magnetic field-induced giant enhancement of electron-phonon energy transfer in strongly disordered conductors.  

PubMed

Relaxation of soft modes (e.g., charge density in gated semiconductor heterostructures, spin density in the presence of magnetic field) slowed down by disorder may lead to giant enhancement of energy transfer (cooling power) between overheated electrons and phonons at low bath temperature. We show that in strongly disordered systems with time-reversal symmetry broken by external or intrinsic exchange magnetic field the cooling power can be greatly enhanced. The enhancement factor as large as 10(2) at magnetic field B~10 T in 2D InSb films is predicted. A similar enhancement is found for the ultrasound attenuation. PMID:24182289

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

2013-10-18

187

Magnetic-field-induced superconductivity in a two-dimensional organic conductor.  

PubMed

The application of a sufficiently strong magnetic field to a superconductor will, in general, destroy the superconducting state. Two mechanisms are responsible for this. The first is the Zeeman effect, which breaks apart the paired electrons if they are in a spin-singlet (but not a spin-triplet) state. The second is the so-called 'orbital' effect, whereby the vortices penetrate into the superconductors and the energy gain due to the formation of the paired electrons is lost. For the case of layered, two-dimensional superconductors, such as the high-Tc copper oxides, the orbital effect is reduced when the applied magnetic field is parallel to the conducting layers. Here we report resistance and magnetic-torque experiments on single crystals of the quasi-two-dimensional organic conductor lambda-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. We find that for magnetic fields applied exactly parallel to the conducting layers of the crystals, superconductivity is induced for fields above 17 T at a temperature of 0.1 K. The resulting phase diagram indicates that the transition temperature increases with magnetic field, that is, the superconducting state is further stabilized with magnetic field. PMID:11309610

Uji, S; Shinagawa, H; Terashima, T; Yakabe, T; Terai, Y; Tokumoto, M; Kobayashi, A; Tanaka, H; Kobayashi, H

2001-04-19

188

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

189

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

PubMed Central

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

2012-01-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

191

Magnetic field induced discontinuous spin reorientation in ErFeO3 single crystal  

NASA Astrophysics Data System (ADS)

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.

Shen, Hui; Cheng, Zhenxiang; Hong, Fang; Xu, Jiayue; Yuan, Shujuan; Cao, Shixun; Wang, Xiaolin

2013-11-01

192

Magnetic-Field-Induced Frequency Shifts for Resonant Tunneling Effects Caused by Surface Plasmons Excitation  

Microsoft Academic Search

This work theoretically investigates how an external magnetic field affects the resonant tunneling of terahertz radiation through a structured semiconductor film that is induced by the surface magnetoplasmons (SMPs). The applied external magnetic field with the Voigt configuration red shifts the frequencies of the resonant tunneling, by exciting the low-frequency branch of the SMP and reducing the effective plasma frequency.

Yung-Chiang Lan

2008-01-01

193

Magnetic field induced by strong transverse plasmons in ultra-relativistic electron-positron plasmas  

NASA Astrophysics Data System (ADS)

Context. We investigated the generation of localized magnetic fields in an ultra-relativistic non-isothermal electron-positron plasma by strong electromagnetic plasmons. Aims: The results obtained can be used to explain the origin of small-scale magnetic fields in the internal shock region of gamma-ray bursts with ultra-relativistic electron positron plasmas. Methods: The generation of magnetic fields was investigated with kinetic Vlasov Maxwell equations. Results: The self-generated magnetic field will collapse for modulation instability, leading to spatially highly intermittent magnetic fluxes, whose characteristic scale is much larger than relativistic plasma skin depth, which in turn is conducive to the generation of the long-life small-scale magnetic fields in the internal shock region of gamma-ray bursts.

Liu, Y.; Li, X. Q.; Liu, S. Q.

2012-08-01

194

Magnetic Field-Induced Superconductivity in the Ferromagnet URhGe  

NASA Astrophysics Data System (ADS)

In several metals, including URhGe, superconductivity has recently been observed to appear and coexist with ferromagnetism at temperatures well below that at which the ferromagnetic state forms. However, the material characteristics leading to such a state of coexistence have not yet been fully elucidated. We report that in URhGe there is a magnetic transition where the direction of the spin axis changes when a magnetic field of 12 tesla is applied parallel to the crystal b axis. We also report that a second pocket of superconductivity occurs at low temperature for a range of fields enveloping this magnetic transition, well above the field of 2 tesla at which superconductivity is first destroyed. Our findings strongly suggest that excitations in which the spins rotate stimulate superconductivity in the neighborhood of a quantum phase transition under high magnetic field.

Lévy, F.; Sheikin, I.; Grenier, B.; Huxley, A. D.

2005-08-01

195

Electro-magnetic-field-induced flow and interfacial instabilities in confined stratified liquid layers  

Microsoft Academic Search

The electro-magneto-hydrodynamic (EMHD) flow and instabilities engendered by the Lorenz force arising from interaction between\\u000a externally applied perpendicular electric and magnetic fields are investigated in layers of two immiscible liquids in a channel.\\u000a A new finite wave-number EMHD instability mode is uncovered by the Orr–Sommerfeld analysis, in addition to the interfacial\\u000a and shear modes which also arise in the pressure-driven

Dipankar Bandyopadhyay; P. Dinesh Sankar Reddy; Ashutosh Sharma; Sang Woo Joo; Shizhi Qian

2011-01-01

196

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

197

Magnetic field induced by elliptical instability in a rotating tidally-distorted sphere  

Microsoft Academic Search

It is usually believed that the geo-dynamo of the Earth or more generally of other planets, is created by the convective fluid motions inside their molten cores. An alternative to this thermal or compositional convection can however be found in the inertial waves resonances generated by the eventual precession of these planets or by the possible tidal distorsions of their

P. LeGal; L. Lacaze; S. LeDizès

2005-01-01

198

Magnetic field induced by elliptical instability in a rotating tidally-distorted sphere  

NASA Astrophysics Data System (ADS)

It is usually believed that the geo-dynamo of the Earth or more generally of other planets, is created by the convective fluid motions inside their molten cores. An alternative to this thermal or compositional convection can however be found in the inertial waves resonances generated by the eventual precession of these planets or by the possible tidal distorsions of their liquid cores. We will review in this paper some of our experimental works devoted to the elliptical instability and present some new results when the experimental fluid is a liquid metal. We show in particular that an imposed magnetic field is distorted by the spin-over mode generated by the elliptical instability. In our experiment, the field is weak (20 Gauss) and the Lorenz force is negligible compared to the inertial forces, therefore the magnetic field does not modify the fluid flow and the pure hydrodynamics growth rates of the instability are recovered through magnetic measurements.

LeGal, P.; Lacaze, L.; LeDizès, S.

2005-01-01

199

Magnetic field induced inversion in the effect of particle size on powder cohesiveness  

NASA Astrophysics Data System (ADS)

Experimental measurements are reported on the tensile yield stress of magnetofluidized beds of fine magnetic powders operated in the cross-flow configuration. In the absence of externally applied magnetic field the yield stress of the powder depends on particle size as expected, i.e., it increases as bead size is decreased. This trend is however inverted when an external magnetic field is applied. It is suggested that the average orientation of interparticle contacts relative to the direction of the field as affected by particle size plays a relevant role on the magnetic yield stress of these systems.

Espin, M. J.; Valverde, J. M.; Quintanilla, M. A. S.; Castellanos, A.

2010-07-01

200

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

SciTech Connect

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.

Jenrow, K.A.; Smith, C.H.; Liboff, A.R. [Oakland Univ., Rochester, MI (United States). Dept. of Physics] [Oakland Univ., Rochester, MI (United States). Dept. of Physics

1996-12-31

201

Quantification of global orientational order in organic solids by magic-angle spinning deuterium NMR with rotor synchronization.  

PubMed

A new method for the characterization of orientational order in organic solids based on magic-angle spinning NMR spectroscopy is introduced. The method is related to the rotor-synchronized magic-angle spinning experiment proposed by Harbison and Spiess [Chem. Phys. Lett. 124, 128 (1986)], but exploits the anisotropy of the deuterium quadrupolar coupling instead of the carbon-13 chemical shielding anisotropy. Magic-angle spinning provides a sensitivity advantage over pseudostatic techniques; using the deuterium quadrupolar coupling makes the method applicable to systems that do not exhibit large carbon chemical shift anisotropies, such as aliphatic polymers. Due to the magnitude of the deuterium quadrupolar coupling, a large number of spinning sidebands can be reliably observed, allowing for a precise determination of the orientational distribution function. Experimental data are analyzed in terms of Wigner matrix basis functions as well as the conjugate orthogonal functions framework. Unidirectionally cold-drawn poly(ethylene) is used as an example to demonstrate the method. PMID:16396546

Nandagopal, Magesh; Utz, Marcel

2005-12-22

202

Indirect detection via spin-1/2 nuclei in solid state NMR spectroscopy: application to the observation of proximities between protons and quadrupolar nuclei.  

PubMed

We present a comprehensive comparison of through-space heteronuclear correlation techniques for solid state NMR, combining indirect detection and single-channel recoupling method. These techniques, named D-HMQC and D-HSQC, do not suffer from dipolar truncation and can be employed to correlate quadrupolar nuclei with spin-1/2 nuclei. The heteronuclear dipolar couplings are restored under magic-angle spinning by applying supercycled symmetry-based pulse sequences (SR412) or simultaneous frequency and amplitude modulation (SFAM). The average Hamiltonian theory (AHT) of these recoupling methods is developed. These results are applied to analyze the performances of D-HMQC and D-HSQC sequences. It is shown that, whatever the magnitude of spin interations, D-HMQC experiment offers larger efficiency and higher robustness than D-HSQC. Furthermore, the spectral resolution in both dimensions of proton detected two-dimensional D-HMQC and D-HSQC spectra can be enhanced by applying recently introduced symmetry-based homonuclear dipolar decoupling schemes that cause a z-rotation of the spins. This is demonstrated by 1H-13C and 1H-23Na correlation experiments on l-histidine and NaH2PO4, respectively. The two-dimensional heteronuclear 1H-23Na correlation spectrum yields the assignment of 23Na resonances of NaH2PO4. This assignment is corroborated by first-principles calculations. PMID:19905016

Lafon, Olivier; Wang, Qiang; Hu, Bingwen; Vasconcelos, Filipe; Trébosc, Julien; Cristol, Sylvain; Deng, Feng; Amoureux, Jean-Paul

2009-11-19

203

Soil Orders  

NSDL National Science Digital Library

Developed by the US Department of Agriculture's Soil Survey Division (SSD), here is a high resolution poster with brief descriptions of the soil orders. Photos of soil profiles accompany descriptions of each order. The soil orders include: Alfisols, Andisols, Aridisols, Entisols, Gelisols, Histosols, Inceptisols, Mollisols, Oxisols, Spodusols, Ultisols, and Vertisols.

204

Order Up  

ERIC Educational Resources Information Center

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

Gibeault, Michael

2005-01-01

205

Apparatus for rapid adjustment of the degree of alignment of NMR samples in aqueous media: Verification with residual quadrupolar splittings in 23Na and 133Cs spectra  

NASA Astrophysics Data System (ADS)

NMR spectra of 23Na + and 133Cs + in gelatine in a silicone rubber tube that was stretched to various extents showed remarkably reproducible resonance multiplicity. The relative intensities of the components of the split peaks had ratios, 3:4:3, and 7:12:15:16:15:12:7, respectively, that conformed with those predicted using a Mathematica program. The silicone-rubber tube was sealed at its lower end by a small rubber stopper and placed inside a thick-walled glass tube. Gelatine was injected in solution into the silicone tube and 'set' by cooling below 30 °C. A plastic thumb-screw held the silicone tube at various degrees of extension, up to ˜2-fold. After constituting the gel in buffers containing NaCl and CsCl, both 23Na and 133Cs NMR spectroscopy revealed that after stretching the initial single Lorentzian line was split into a well-resolved triplet and a heptet, respectively. This was interpreted as being due to coupling between the electric quadrupoles of the nuclei and the average electric field gradient tensor of the collagen molecules of gelatine; these molecules became progressively more aligned in the direction of the main magnetic field, B0, of the vertical bore magnet, as the gel was stretched. This apparatus provides a simple way of demonstrating fundamental physical characteristics of quadrupolar cations, some characteristics of gelatine under stretching, and a way to invoke static distortion of red blood cells. It should be useful with these and other cell types, for studies of metabolic and membrane transport characteristics that may change when the cells are distorted, and possibly for structural studies of macromolecules.

Kuchel, Philip W.; Chapman, Bogdan E.; Müller, Norbert; Bubb, William A.; Philp, David J.; Torres, Allan M.

2006-06-01

206

Ordering Game  

NSDL National Science Digital Library

This interactive game gives students practice in ordering sets of whole numbers, integers, fractions, decimals, and the sizes of circles. Students re-order a group of numbers or objects in a line from least to greatest by dragging them. The activity is timed and points are awarded.

2011-01-01

207

Ordering numbers  

NSDL National Science Digital Library

Khan Academy Exercise bank - Ordering numbers Students are able to use the knowledge map and progress tracking tool to record and support their learning goals. Hints are provided and supporting video tutorials are identified and linked.

Khan, Sal

2011-04-01

208

Ordering Fractions  

NSDL National Science Digital Library

This interactive Flash applet develops a student's fractional understanding and provides practice with comparing and ordering fractions. The learner is given five fractions in "frames" and must place them on the wall hooks in order from least to greatest. If help is needed, a student can enter the Testing Room and manipulate a pair of pipes to see and/or compare the two fractions side by side.

Bunker, Dan

2011-01-01

209

Long-range antiferromagnetic order in the frustrated XY pyrochlore antiferromagnet Er2Ge2O7  

NASA Astrophysics Data System (ADS)

A cubic Er2Ge2O7 pyrochlore was prepared under high-pressure and high-temperature conditions and its magnetic ground state was investigated by measurements of specific heat, dc and ac magnetic susceptibility as functions of temperature, pressure, and magnetic field. We found that Er2Ge2O7 undergoes a long-range antiferromagnetic transition at TN ? 1.4 K, which can be further enhanced by applying external physical pressure. On the other hand, application of external magnetic fields suppresses the antiferromagnetic order to zero temperature around Hc ? 2.3 T, where a magnetic-field-induced spin-flop transition was observed. Hc increases accordingly with increasing TN under external pressure. A comparison of the magnetic ground states and structural variations along the isostructural series Er2B2O7 (B = Sn, Ti, Ge) together with the high-pressure study on Er2Ge2O7 indicated that the magnetic properties of these highly frustrated XY pyrochlore antiferromagnets are very sensitive to the minute structural changes that determine the anisotropic exchange interactions and the local crystal-electric-field environments of Er3+ ions.

Li, X.; Li, W. M.; Matsubayashi, K.; Sato, Y.; Jin, C. Q.; Uwatoko, Y.; Kawae, T.; Hallas, A. M.; Wiebe, C. R.; Arevalo-Lopez, A. M.; Attfield, J. P.; Gardner, J. S.; Freitas, R. S.; Zhou, H. D.; Cheng, J.-G.

2014-02-01

210

Dynamics of a quadrupolar glass  

Microsoft Academic Search

Substitutional disorder in an orientationally disordered crystal generates static random strain fields. Strains cause scattering of orientational and displacive waves. The resulting friction processes may lead to structural arrest (nonergodic instability) at a threshold temperature Tf. The slow dynamics associated with structural arrest is studied. The scattering law exhibits a dynamic central peak. The influence of microscopic relaxation processes on

C. Bostoen; K. H. Michel

1991-01-01

211

In Order  

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.

2011-05-01

212

Direct and quantitative determination of the orbital ordering in CeB6 by X-ray diffraction  

NASA Astrophysics Data System (ADS)

Results of non-resonant X-ray Bragg diffraction by CeB6 are reported. This material has been described in terms of a simple antiferro-quadrupolar order below TQ = 3.2 K. We determine for the first time, directly and quantitatively the orbital ordering in this material. In particular, we find direct evidence for a simultaneous ordering of a quadrupole (QP) and a hexadecapole (HDP) moments below TQ. From a strong dependence of the Bragg intensity on applied magnetic field in phase II, we conclude that octupole (OP) moments are induced and are coupled to the QP and HDP moments. When spontaneous magnetic dipole order sets in below TN = 2.4 K (phase III), a large enhancement of the Bragg intensity confirms the coupling between the dipole and the QP, OP and HDP moments.

Tanaka, Y.; Staub, U.; Katsumata, K.; Lovesey, S. W.; Lorenzo, J. E.; Narumi, Y.; Scagnoli, V.; Shimomura, S.; Tabata, Y.; Onuki, Y.; Kuramoto, Y.; Kikkawa, A.; Ishikawa, T.; Kitamura, H.

2004-12-01

213

Simulated MR magnetic field induces steady-state changes in brain dynamics: Implications for interpretation of functional MR studies  

Microsoft Academic Search

We examined whether a magnetic field comparable to one of the fields produced during MRI induced steady-state changes in brain electrical activity while the field was applied (called a presence effect to distinguish it from evoked potentials). The electroencephalogram was measured from standard scalp locations in the presence and absence of 100-200 mT, 60 Hz, and the effect of the

Andrew A. Marino; Simona Carrubba; Clifton Frilot; Andrew L. Chesson; Eduardo Gonzalez-Toledo

2010-01-01

214

Magnetic field-induced solvothermal synthesis of one-dimensional assemblies of NiCo alloy microstructures  

Microsoft Academic Search

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,

Ming Jun Hu; Bin Lin; Shu Hong Yu

2008-01-01

215

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

NASA Astrophysics Data System (ADS)

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

Olendski, O.

2011-06-01

216

Resonant alteration of supercurrent in guiding structures with complex de Gennes distance and its magnetic-field-induced restoration  

NASA Astrophysics Data System (ADS)

Properties of the superconducting 2D disk and 3D wire are calculated within the framework of linearized Ginzburg-Landau theory with the complex de Gennes distance ? in the boundary condition. As a result, the self-adjointness of the Hamiltonian is lost, its eigenvalues E become complex too and the discrete bound states of the disk turn into the quasibound states with their lifetime defined by the eigeneneries imaginary parts Ei. Accordingly, the longitudinal supercurrent undergoes alteration with its attenuation/amplification being Ei-dependent too. It is shown that Ei as a function of the de Gennes imaginary part ?i exhibits a pronounced sharp extremum with its magnitude being the largest for the zero real part ?r of the de Gennes distance. Increasing magnitude of ?r quenches the Ei-?i resonance and at large ?r the eigenenergies E approach the asymptotic real values independent of the de Gennes length imaginary component. The extremum is also wiped out by the applied longitudinal uniform magnetic field. The finite lifetime of the disk quasibound states stems from the ?i-induced currents flowing through the superconductor boundary. The effect can be observed in the superconductors by applying to them the external electric field.

Olendski, Oleg

2011-03-01

217

Experimental evidence for involvement of nitric oxide in low frequency magnetic field induced obsessive compulsive disorder-like behavior.  

PubMed

It is well documented that extremely low frequency magnetic field (ELF MF) produced effects on the function of nervous system in humans and laboratory animals. Dopaminergic and serotonergic pathways have been implicated in obsessive compulsive disorder (OCD). Recently involvement of nitric oxide (NO) in OCD-like behavior is suggested. Hence, the present study was carried out to understand the involvement of dopamine, serotonin and NO in ELF MF induced OCD-like behavior. Swiss albino mice were exposed to ELF MF (50Hz, 10G) for 8h/day for 7, 30, 60, 90 and 120days by subjecting them to Helmholtz coils. OCD-like behavior was assessed in terms of marble burying behavior (MBB) test. Results revealed that ELF MF induced time dependant MBB, on 7th, 30th, 60th, 90th, and 120th exposure day. Further, levels of dopamine, serotonin and NO after 120days of ELF MF exposure were determined in the regions of the brain. The neurohumoral studies revealed that exposure to ELF MF increased NO levels in cortex, hippocampus and hypothalamus, and levels of dopamine and serotonin remain unaffected. As OCD-like behavior after ELF MF exposure was associated with higher levels of NO with no significant change in serotonin and dopamine. The effect of such exposure was studied in groups concurrently treated with NO modulators, NO precursor, l-ARG (400mg/kg) or NOS inhibitor, l-NAME (15.0mg/kg) or 7-NI (10.0mg/kg). These treatments revealed that NO precursor exacerbated and NOS inhibitors attenuated ELF MF induced OCD-like behavior with corresponding changes in the levels of NO. PMID:24780504

Salunke, Balwant P; Umathe, Sudhir N; Chavan, Jagatpalsingh G

2014-07-01

218

Magnetic field-induced T cell receptor clustering by nanoparticles enhances T cell activation and stimulates antitumor activity.  

PubMed

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

Perica, Karlo; Tu, Ang; Richter, Anne; Bieler, Joan Glick; Edidin, Michael; Schneck, Jonathan P

2014-03-25

219

The role of eddy currents and nanoparticle size on AC magnetic field-induced reflow in solder/magnetic nanocomposites  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticle (MNP)-based solder composites can facilitate solder reflow in AC magnetic fields. We compare power loss in a solder composite sample with MNP loading of different particle size distribution. Scaling of solder composite samples shows that, for smaller samples, power loss is not sufficient to realize solder reflow temperature. Additional heating can be derived from eddy current losses in Cu planes in the substrate board. Eddy current heating in Cu sheets of various thickness were evaluated to quantify their effect for low-temperature electronic assembly.

Habib, A. H.; Xu, S.; Walker, E.; Ondeck, M.; Swaminathan, R.; McHenry, M. E.

2012-04-01

220

Magnetic Field-Induced Spectroscopy of Forbidden Optical Transitions with Application to Lattice-Based Optical Atomic Clocks  

Microsoft Academic Search

We develop a method of spectroscopy that uses a weak static magnetic field to enable direct optical excitation of forbidden electric-dipole transitions that are otherwise prohibitively weak. The power of this scheme is demonstrated using the important application of optical atomic clocks based on neutral atoms confined to an optical lattice. The simple experimental implementation of this method---a single clock

A. V. Taichenachev; V. I. Yudin; C. W. Oates; C. W. Hoyt; Z. W. Barber; L. Hollberg

2006-01-01

221

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

NASA Astrophysics Data System (ADS)

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.

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

2008-02-01

222

50 Hz-Sinusoidal magnetic field induced effects on the bioelectric activity of single unit neurone cells  

NASA Astrophysics Data System (ADS)

Neurones recruiting and synchronized bioelectric activity recorded from Helix aspersa brain ganglia, under exposure to 50 Hz sinusoidal magnetic fields of 1-15 mT intensity, is reported. We show recruiting responses from single neurones and the synchronization of pairs of neurones activity. Experimental evidence and model theoretical explanation for the spreading of synchronization are presented.

Azanza, Mar?´a. J.; Calvo, Ana C.; del Moral, A.

2001-05-01

223

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

SciTech Connect

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

Olendski, O., E-mail: oolendski@ksu.edu.sa [King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box 2454, Riyadh 11451 (Saudi Arabia)

2011-06-15

224

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

EPA Science Inventory

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

225

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

EPA Science Inventory

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

226

Magnetic Field-Induced Phase Transition of Quantum Spin System Cu2Cl4.H8C4SO2  

NASA Astrophysics Data System (ADS)

The magnetic properties of Cu2Cl4.H8C4SO2 are described by an S = 1/2 double spin chain with strong exchange interactions along the leg direction. This system has a singlet ground state with an excitation gap of ?/kB = 5.13 K. We have measured the magnetization and the specific heat of Cu2Cl4.H8C4SO2. The magnetic phase transition due to interchain interactions was observed for H > 4 T. Magnetic phase diagrams were obtained for H ? b- and c-axes. The phase boundaries for these two different field directions can be represented by the power law (g/2)[HN(T) - Hg] ~ T? with (g/2)Hg = 3.83 T and ? = 1.98. The experimental exponent ? = 1.98 is somewhat larger than the value ?BEC = 3/2 predicted by the magnon Bose-Einstein condensation theory.

Fujisawa, Masashi; Tanaka, Hidekazu; Sakakibara, Toshiro

2006-09-01

227

Effects of T2-relaxation in MAS NMR spectra of the satellite transitions for quadrupolar nuclei: a 27Al MAS and single-crystal NMR study of alum KAl(SO 4) 2 · 12H 2O  

NASA Astrophysics Data System (ADS)

Asymmetries in the manifold of spinning sidebands (ssbs) from the satellite transitions have been observed in variable-temperature 27Al MAS NMR spectra of alum (KAl(SO 4) 2 · 12H 2O), recorded in the temperature range from -76 to 92 °C. The asymmetries decrease with increasing temperature and reflect the fact that the ssbs exhibit systematically different linewidths for different spectral regions of the manifold. From spin-echo 27Al NMR experiments on a single-crystal of alum, it is demonstrated that these variations in linewidth originate from differences in transverse ( T2) relaxation times for the two inner ( m = 1/2 ? m = 3/2 and m = -1/2 ? m = -3/2) and correspondingly for the two outer ( m = 3/2 ? m = 5/2 and m = -3/2 ? m = -5/2) satellite transitions. T2 relaxation times in the range 0.5-3.5 ms are observed for the individual satellite transitions at -50 °C and 7.05 T, whereas the corresponding T1 relaxation times, determined from similar saturation-recovery 27Al NMR experiments, are almost constant ( T1 = 0.07-0.10 s) for the individual satellite transitions. The variation in T2 values for the individual 27Al satellite transitions for alum is justified by a simple theoretical approach which considers the cross-correlation of the local fluctuating fields from the quadrupolar coupling and the heteronuclear ( 27Al- 1H) dipolar interaction on the T2 relaxation times for the individual transitions. This approach and the observed differences in T2 values indicate that a single random motional process modulates both the quadrupolar and heteronuclear dipolar interactions for 27Al in alum at low temperatures.

Andersen, Morten Daugaard; Jakobsen, Hans J.; Skibsted, Jørgen

2005-04-01

228

Continuous-time Monte Carlo and spatial ordering in driven lattice gases: Application to driven vortices in periodic superconducting networks  

NASA Astrophysics Data System (ADS)

We consider the two-dimensional (2D) classical lattice Coulomb gas as a model for magnetic field induced vortices in 2D superconducting networks. Two different dynamical rules are introduced to investigate driven diffusive steady states far from equilibrium as a function of temperature and driving force. The resulting steady states differ dramatically depending on which dynamical rule is used. We show that the commonly used driven diffusive Metropolis Monte Carlo dynamics contains unphysical intrinsic randomness that destroys the spatial ordering present in equilibrium (the vortex lattice) over most of the driven phase diagram. A continuous time Monte Carlo (CTMC) method is then developed, which results in spatially ordered driven states at low temperature in finite sized systems. We show that CTMC is the natural discretization of continuum Langevin dynamics, and argue that it gives the correct physical behavior when the discrete grid represents the minima of a periodic potential. We use detailed finite size scaling methods to analyze the spatial structure of the steady states. We find that finite size effects can be subtle and that very long simulation times can be needed to arrive at the correct steady state. For particles moving on a triangular grid, we find that the ordered moving state is a transversely pinned smectic that becomes unstable to an anisotropic liquid on sufficiently large length scales. For particles moving on a square grid, the moving state is a similar smectic at large drives, but we find evidence for a possible moving solid at lower drives. We find that the driven liquid on the square grid has long range hexatic order, and we explain this as a specifically nonequilibrium effect. We show that, in the liquid, fluctuations about the average center of mass motion are diffusive in both the transverse and longitudinal directions.

Gotcheva, Violeta; Wang, Yanting; Wang, Albert T. J.; Teitel, S.

2005-08-01

229

Sodium Ions in Ordered Environments in Biological Systems: Analysis of 23Na NMR Spectra  

NASA Astrophysics Data System (ADS)

Experimentsthat selectively excite I = {3}/{2} nuclei exhibiting residual quadrupolar splittings are used to acquire 23Na NMR spectra from a range of biologically relevant samples containing sodium in ordered environments. Three complementary approaches to the analysis of such spectra are described: (i) measurement of relaxation rates, (ii) extraction of homogeneous linewidths from two-dimensional Jeener-Broekaert spectra, and (iii) simultaneous fitting of detailed theoretical functions to a series of one-dimensional Jeener-Broekaert spectra. Analysis of relaxation rates provides evidence for compartmentation in bovine nasal cartilage. Each approach is used to demonstrate the presence of anisotropy in transverse relaxation in porcine tendon. For certain samples containing collagen, a good theoretical fit to the spectra was obtained using a model that allows for anisotropic relaxation by including the effects of slow lateral and radial diffusion.

Kemp-Harper, Richard; Wickstead, Bill; Wimperis, Stephen

1999-10-01

230

Transformations in the Gd{sub 5}(Si{sub 1.95}Ge{sub 2.05}) alloy induced by the temperature and magnetic-field cycling through the first-order magnetic-martensitic phase transition  

SciTech Connect

Temperature dependencies of the dc electrical resistivity, dc magnetization, and heat capacity of virgin Gd{sub 5}(Si{sub 1.95}Ge{sub 2.05}) samples and after they had been cycled through the first-order phase transition by varying temperature or magnetic field were studied. The virgin sample shows a transition from the low-temperature phase {alpha} to the high-temperature, low-resistance phase {beta}{prime}. After several temperature and/or magnetic field induced cycles of the Gd{sub 5}(Si{sub 1.95}Ge{sub 2.05}) alloy through the first-order phase transition, the {alpha} phase transforms to {beta}'' where {beta}'' is the high-resistance phase. The dc magnetization and zero magnetic field heat capacity data indicate that the temperature of the {alpha}{leftrightarrow}{beta}'' phase transition is lower by {approx}2 K relative to {alpha}{leftrightarrow}{beta}{prime}, while the electrical resistance shows {approx}7 K temperature difference. The observed phenomena are discussed based on the mechanism of the simultaneous magnetic/crystallographic phase transition in Gd{sub 5}(Si{sub x}Ge{sub 4-x}).

Levin, E. M.; Pecharsky, A. O.; Pecharsky, V. K.; Gschneidner, K. A.

2001-02-01

231

Precision search for magnetic order in the pseudogap regime of La2-xSrxCuO4 by muon spin relaxation  

NASA Astrophysics Data System (ADS)

We report a high-precision search for orbital-like magnetic order in the pseudogap region of La2-xSrxCuO4 single crystals using zero-field muon spin relaxation (ZF-?SR). In contrast to previous studies of this kind, the effects of the dipolar and quadrupolar interactions of the muon with nearby nuclei are calculated. ZF-?SR spectra with a high number of counts were also recorded to determine whether a magnetically ordered phase exists in dilute regions of the sample. Despite these efforts, we find no evidence for static magnetic order of any kind in the pseudogap region above the hole-doping concentration p=0.13.

Huang, W.; Pacradouni, V.; Kennett, M. P.; Komiya, S.; Sonier, J. E.

2012-03-01

232

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

SciTech Connect

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.

Agzamova, P. A., E-mail: polina_agzamova@usu.ru; Leskova, Yu. V.; Nikiforov, A. E. [Ural Federal University (Russian Federation)

2013-05-15

233

FOOTBALL BANNING ORDERS, PROPORTIONALITY, AND PUBLIC ORDER  

Microsoft Academic Search

This paper provides a critical analysis of the U.K. legislation on Football Banning Orders. The historical development of this legislation is outlined and concerns are raised about its impact upon civil liberties and human rights. The paper then outlines a body of research on crowd psychology, public order policing and football 'disorder' that questions the determining role of the Banning

CLIFFORD STOTT

234

Higher order decompositions of ordered operator exponentials  

NASA Astrophysics Data System (ADS)

We present a decomposition scheme based on Lie-Trotter-Suzuki product formulae to approximate an ordered operator exponential with a product of ordinary operator exponentials. We show, using a counterexample, that Lie-Trotter-Suzuki approximations may be of a lower order than expected when applied to problems that have singularities or discontinuous derivatives of appropriate order. To address this problem, we present a set of criteria that is sufficient for the validity of these approximations, prove convergence and provide upper bounds on the approximation error. This work may shed light on why related product formulae fail to be as accurate as expected when applied to Coulomb potentials.

Wiebe, Nathan; Berry, Dominic; Høyer, Peter; Sanders, Barry C.

2010-01-01

235

Mean residual life ordering  

Microsoft Academic Search

A new partial ordering among life distributions in terms of their mean residual life is introduced. This ordering is weaker\\u000a than the hazard rate ordering but it is stronger than the variability ordering. Characterizations of the DMRL and NBUE distribution\\u000a are given.

Abdulhamid A. Alzaid

1988-01-01

236

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

NASA Astrophysics Data System (ADS)

Results of temperature- and magnetic field-dependent strain measurements across the first-order antiferromagnetic to ferromagnetic phase transition in Fe0.955Ni0.045Rh are presented. Distinct thermal and magnetic field hystereses are observed in the measured strain across the phase transition. The minor hysteresis loops inside the hysteretic regime across the temperature-driven transition are modeled using the Preisach model of hysteresis. The applicability of the Preisach model to explain the general features of minor hysteresis loops is discussed for a disorder influenced first-order transition. The minor hysteresis loops show the property of retaining the memory of the starting or end point of the temperature cycle followed within the hysteretic region. A larger temperature excursion within the hysteretic region wipes out the memory of a smaller temperature cycle which contains one of the extrema of the larger cycle. The end-point memory and the wiping-out property of the minor hysteresis loops can be described quite well within the Preisach model, irrespective of the temperature history followed to reach a particular starting point. Thermo-magnetic history effects across the magnetic field-induced transition are explained, which will enable the choice of the starting point of an experimental cycle in the field-temperature phase space so as to achieve the desired functionality. Our results highlight the necessity to understand the influence of disorder on a first-order phase transition so as to achieve a repeatable performance of materials whose functionalities are based on such a transition.

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

2012-05-01

237

Lattice solitons with quadrupolar intersite interactions  

NASA Astrophysics Data System (ADS)

We study two-dimensional (2D) solitons in the mean-field models of ultracold gases with long-range quadrupole-quadrupole interaction (QQI) between particles. The condensate is loaded into a deep optical-lattice (OL) potential, therefore the model is based on the 2D discrete nonlinear Schrödinger equation with contact on site and long-range intersite interactions, which represent the QQI. The quadrupoles are built as pairs of electric dipoles and antidipoles orientated perpendicular to the 2D plane to which the gas is confined. Because the quadrupoles interact with the local gradient of the external field, they are polarized by an inhomogeneous dc electric field that may be supplied by a tapered capacitor. Shapes, stability, mobility, and collisions of fundamental discrete solitons are studied by means of systematic simulations. In particular, threshold values of the norm, which are necessary for the existence of the solitons, are found and anisotropy of their static and dynamical properties is explored. As concerns the mobility and collisions, we analyze such properties for discrete solitons on 2D lattices with long-range intersite interactions. Estimates demonstrate that the setting can be realized under experimentally available conditions, predicting solitons built of ˜10000 particles.

Li, Yongyao; Liu, Jingfeng; Pang, Wei; Malomed, Boris A.

2013-12-01

238

Order Statistic Experiment  

NSDL National Science Digital Library

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.

Siegrist, Kyle

239

Order of Operations Quiz  

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.

240

Ordered Simple Plot  

NSDL National Science Digital Library

Plot ordered pairs on the graph, and they will be connected in the order that they are input. This enables you to decide how the pairs should be connected, rather than having the computer connect them from left to right.

241

First-order inflation  

SciTech Connect

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.

Kolb, E.W. (Fermi National Accelerator Lab., Batavia, IL (USA) Chicago Univ., IL (USA). Enrico Fermi Inst.)

1990-09-01

242

First-order inflation  

NASA Technical Reports Server (NTRS)

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, Edward W.

1991-01-01

243

Order of Operations  

NSDL National Science Digital Library

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 ...

Nieman, Mrs.

2008-10-05

244

Orderly Career Opportunities.  

ERIC Educational Resources Information Center

The hierarchy of positions in an educational organization makes it possible to have an orderly career, which is traced out through a series of related positions. A differentiated salary schedule provides the incentive to pursue an orderly career. Barriers to an orderly career are of five types: assessment, education, seniority, experience, and…

Carlson, Richard O.

245

The Importance of Order  

ERIC Educational Resources Information Center

Children's places need ordered time and space that furthers the program goals while making the program a pleasant place to live and work for all those (large and small) who inhabit the program. The order provides a comforting framework that does not harshly interrupt the activities of children, instead the order allows for more experiences and for…

Greenman, Jim

2006-01-01

246

Nash social welfare orderings  

Microsoft Academic Search

The paper considers the problem of description of social welfare orderings (SWOs) on the entire utility (Euclidean) space Rn satisfying Scale Independence. These orderings and the functions representing them are called the Nash social welfare orderings and the Nash social welfare functions (SWFs), respectively. The more properties of the SWOs into consideration are Strong Pareto and two variants of weakening

Natalia Naumova; Elena Yanovskaya

2001-01-01

247

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

NASA Astrophysics Data System (ADS)

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

Mandal, Aparajita; Chaudhuri, Partha

2013-07-01

248

Characterizing limit order prices  

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

249

Color ordering in QCD  

NASA Astrophysics Data System (ADS)

We derive color decompositions of arbitrary tree and one-loop QCD amplitudes into color-ordered objects called primitive amplitudes. Furthermore, we derive general fermion flip and reversion identities spanning the null space among the primitive amplitudes and use them to prove that all color-ordered tree amplitudes of massless QCD can be written as linear combinations of color-ordered tree amplitudes of N=4 super Yang-Mills theory.

Schuster, Theodor

2014-05-01

250

Order, Disorder and Confinement  

SciTech Connect

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

D'Elia, M. [Dipartimento di Fisica dell'Universita di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); INFN, Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Di Giacomo, A.; Pica, C. [Dipartimento di Fisica dell'Universita di Pisa, largo Pontecorvo 3, I-56127 Pisa (Italy); INFN, Sezione di Pisa, largo Pontecorvo 3, I-56127 Pisa (Italy)

2006-01-12

251

Finite Order Statistic Experiment  

NSDL National Science Digital Library

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.

Siegrist, Kyle

252

Bioregions and World Order.  

ERIC Educational Resources Information Center

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

Breakthrough, 1985

1985-01-01

253

Compare and Order Fractions  

NSDL National Science Digital Library

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).

2011-01-01

254

Automata on Linear Orderings  

Microsoft Academic Search

Abstract We consider words indexed by linear orderings. These extend finite, (bi-)infinite words and words on ordinals. We introduce finite automata and rational expressions for these words. We prove that for countable scattered linear orderings, these two notions are equivalent. This result extends Kleene’s theorem.

Véronique Bruyère; Olivier Carton

2001-01-01

255

Automata on Linear Orderings  

Microsoft Academic Search

We consider words indexed by linear orderings. These extend finite, (bi-)infinite words and words on ordinals. We introduce finite automata and rational expressions for these words. We prove that for countable scattered linear orderings, these two notions are equivalent. This result extends Kleene's theorem.

Véronique Bruyère; Olivier Carton

2002-01-01

256

Exploring Order of Operations  

NSDL National Science Digital Library

This interactive activity demonstrates the order of operations. The game asks students to click on the correct operation in a series of mathematical problems. Correct answers will increase the user's time for the next game. Students should have some knowledge of the order of operations prior to doing this activity. Two worksheets are also available for print or download in PDF file format.

2012-08-06

257

Narcissism and birth order.  

PubMed

The purpose of this investigation was to clarify the relationship between birth-order position and the development of narcissism, while refining research and theory. The relationship between birth-order status and narcissism was examined with a sample of 79 undergraduate students (55 women and 24 men). These subjects were placed in one of the four following birth-order categories of firstborn, second-born, last-born, and only children. These categories were chosen given their significance in Adlerian theory. Each subject completed the Narcissistic Personality Inventory and a demographic inventory. Based on psychodynamic theory, it was hypothesized that firstborn children were expected to score highest, but statistical significance was not found for an association between narcissism and birth order. Further research is urged to investigate personality theory as it relates to parenting style and birth order. PMID:9148293

Eyring, W E; Sobelman, S

1996-04-01

258

Magnetic field-induced degradation of magnetic properties in molecular beam epitaxy grown FeMn/NiFe exchange-coupled bilayers  

NASA Astrophysics Data System (ADS)

Degradation of magnetic properties has been observed in molecular beam epitaxy grown Si(111)/Cu 2 nm/NiFe 6 nm/FeMn (2-12)nm/Cu 5 nm exchange-biased bilayers during magnetic field sweeping. When the samples are subjected to several magnetic field sweeps, there is blister-shaped deterioration of the film surface quality and the magnetometry data suggest an increasing fraction of the NiFe moments become unpinned from the FeMn layer. Comprehensive characterization using high resolution electron microscopy and electron probe microanalysis revealed that this degradation has been initiated by delamination between the NiFe and FeMn layers and crack formation as a result of magnetostrictive stress buildup during the magnetic field sweeps. Further degradation can then be attributed to the formation of the nonmagnetic FeMn oxide by oxidation of the bare FeMn around the delaminated area.

Choi, Y. S.; Petford-Long, A. K.; Ward, R. C. C.

2003-05-01

259

Microwave Spectroscopy Evidence of Superconducting Pairing in the Magnetic-Field-Induced Metallic State of InOx Films at Zero Temperature  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

260

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

NASA Astrophysics Data System (ADS)

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

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

1995-09-01

261

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

262

Magnetic Field-Induced Precipitation Behaviors of Alloy Carbides M2C, M3C, and M6C in a Molybdenum-Containing Steel  

NASA Astrophysics Data System (ADS)

The effect of a 12-T high magnetic field on alloy carbide precipitation in an Fe-C-Mo alloy during tempering at an intermediate temperature was investigated. Thin foils and carbon extraction replicas of the treated specimens were examined by transmission electron microscopy (TEM). The results show that the applied high field effectively promoted the precipitation of (Fe,Mo)6C alloy carbide. The concentration of Fe atom in Fe6- x Mo x C carbide is increased whereas that of Mo atom decreased when the high magnetic field was applied. However, the high magnetic field almost had no detectable influence on the atom concentration in (Fe,Mo)2C and (Fe,Mo)3C carbides. First principle calculations have been performed to calculate the magnetic moment per iron atom of the carbides to explore the origin of the effect of the magnetic field. The influence of the high magnetic field on the precipitation behaviors of alloy carbides was closely related to the magnetic moment of (Fe,Mo)2C, (Fe,Mo)3C, and (Fe,Mo)6C. The magnetic field promotes the formation of the carbides with high total magnetic moment. The effect of the high magnetic field on the substitutional solute atom (Fe and Mo) concentration change in the three alloy carbides was attributed to their magnetization differences per Fe atom.

Hou, T. P.; Li, Y.; Zhang, Y. D.; Wu, K. M.

2014-05-01

263

Magnetic field induced percolation in Pr0.67Ca0.33MnO3 by small angle magnetic neutron scattering  

NASA Astrophysics Data System (ADS)

We have studied by small angle neutron scattering the evolution induced by the application of magnetic field of the coexistence of ferromagnetism and antiferromagnetism in a crystal of Pr0.67Ca0.33MnO3. The results are compared to magnetic measurements, which provide the evolution of the ferromagnetic fraction. These results show that the growth of the ferromagnetic phase corresponds to an increase of the thickness of the ferromagnetic ``cabbage'' sheets.

Simon, Ch.; Mercone, S.; Hardy, V.; Martin, C.; Saurel, D.; Brulet, A.

2004-05-01

264

Magnetic field induced percolation in Pr 0.67Ca 0.33MnO 3 by small angle magnetic neutron scattering  

NASA Astrophysics Data System (ADS)

We have studied by small angle neutron scattering the evolution induced by the application of magnetic field of the coexistence of ferromagnetism and antiferromagnetism in a crystal of Pr 0.67Ca 0.33MnO 3. The results are compared to magnetic measurements, which provide the evolution of the ferromagnetic fraction. These results show that the growth of the ferromagnetic phase corresponds to an increase of the thickness of the ferromagnetic ''cabbage'' sheets.

Simon, Ch; Mercone, S.; Hardy, V.; Martin, C.; Saurel, D.; Brulet, A.

265

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

PubMed

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

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

2013-08-01

266

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

NASA Astrophysics Data System (ADS)

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

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

267

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

SciTech Connect

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.

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

268

Influence of Temperature during Electric- and Magnetic-Field-Induced Alteration of Calcium-Ion Release from In vitro Brain Tissue.  

National Technical Information Service (NTIS)

A technique based on release of calcium ions from in vitro preparations of avian brain tissues has been used by several investigators to demonstrate a biological effect of weak electric and magnetic fields. When the tissues have been exposed to ELF-modula...

C. F. Blackman S. G. Benane D. E. House

1991-01-01

269

Magnetic-field-induced charged exciton studies in a GaAs/Al{sub 0.3}Ga{sub 0.7}As single heterojunction  

SciTech Connect

The magnetophotoluminescence (MPL) behavior of a GaAs/Al{sub 0.3}Ga{sub 0.7}As single heterojunction has been investigated to 60 T. We observed negatively charged singlet (X{sub s}{sup -}) and triplet (X{sub t}{sup -}) exciton states that are formed at high magnetic fields beyond the {nu}=1 quantum Hall state. The variation of the charged exciton binding energies are in good agreement with theoretical predictions. The MPL transition intensities for the X{sub s}{sup -} and X{sub t}{sup -} states showed variations (maxima and minima) at the {nu}=1/3 and 1/5 fractional quantum Hall states as a consequence of a large reduction of electron-hole screening at these filling factors. (c) 2000 The American Physical Society.

Kim, Yongmin [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Munteanu, F. M. [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States) [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Perry, C. H. [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States) [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Rickel, D. G. [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Simmons, J. A. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Reno, J. L. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)

2000-02-15

270

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

SciTech Connect

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

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

1999-05-25

271

Court Ordered Desegregation  

ERIC Educational Resources Information Center

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.

Reber, Sarah J.

2005-01-01

272

Programming Languages: Marching Orders  

NSDL National Science Digital Library

In this activity about computer programming, learners follow instructions in a variety of ways in order to successfully draw figures. Through these exercises, learners will experience some of the often frustrating aspects of computer programming.

Bell, Tim; Witten, Ian; Fellows, Mike; Adams, Robyn; Mckenzie, Jane

2005-01-01

273

Liquid metals: Supercool order  

NASA Astrophysics Data System (ADS)

Electron microscopy reveals ordered layering imposed on liquid aluminium at the interface with a solid. A better understanding of this effect will have important consequences for applications ranging from fluid flow to casting.

Greer, A. Lindsay

2006-01-01

274

Order without a cause  

NASA Astrophysics Data System (ADS)

The pervasiveness of order in landscapes, from striking patterns such as fields of sand dunes to less eye-catching examples such as tussock tundra, motivates efforts to find its cause. However, studying order as an abstract, overarching structure common to many similar systems or as emerging from fundamental physical processes reveals little about the dynamics of specific landscapes, because order is an irreducible property of the dynamics of a system and not a product of causal relations between different aspects of the system. This hypothesis is based on the view that the order of a landscape is the extent to which it is organized into a hierarchy of scale-separated behaviors. With increasing level in the hierarchy, time scale increases and the number of degrees of freedom decreases. The lone relations between adjacent levels connect only the fast-scale variables of the lower level with the slow-scale dynamics of the upper level (through self-organization/slaving). The dynamics at each level is an independent property of the system, not an effect caused by dynamics at any other level. Order is quantified using the number and time scales of levels in the hierarchy. Ice-rich permafrost terrain of the Kitluk drainage basin in Bering Land Bridge National Preserve, Alaska, illustrates a highly developed hierarchical order without a cause. The terrain has numerous levels, ranging from soil particle motion (~ seconds) to integrated lake drainage networks (10 ka). Using our concept of order, measurements over a range of locations reveal that this seemingly unpatterned landscape contrasts with many patterned systems, such as fields of sorted patterned ground in Western Spitsbergen, where order is less developed. Supported by the Andrew W. Mellon Foundation.

Werner, B.; Kitluk, A.; Plug, L. J.

2003-12-01

275

Order the Decimals  

NSDL National Science Digital Library

In this interactivity, students are required to order eight decimals from least to greatest by numbering them. Students can check answers and pieces of a picture are revealed behind their correct choices. Students can request a hint or to see all eight numbers in order and play again. Quia Web offers free shared activities with teacher-made content. Subscriptions allow members to create or alter the content of the games.

2011-01-01

276

Leftist Canonical Ordering  

Microsoft Academic Search

\\u000a Canonical ordering is an important tool in planar graph drawing and other applications. Although a linear-time algorithm to\\u000a determine canonical orderings has been known for a while, it is rather complicated to understand and implement, and the output\\u000a is not uniquely determined. We present a new approach that is simpler and more intuitive, and that computes a newly defined\\u000a leftist

Melanie Badent; Michael Baur; Ulrik Brandes; Sabine Cornelsen

2009-01-01

277

Static Partial Order Reduction  

Microsoft Academic Search

The state space explosion problem is central to automatic verification algorithms. One of the successful techniques to abate\\u000a this problem is called ‘partial order reduction’. It is based on the observation that in many cases the specification of concurrent\\u000a programs does not depend on the order in which concurrently executed events are interleaved. In this paper we present a new

Robert P. Kurshan; Vladimir Levin; Marius Minea; Doron Peled; Hüsnü Yenigün

1998-01-01

278

Concomitant Ordering and Symmetry Lowering  

ERIC Educational Resources Information Center

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…

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

2008-01-01

279

The birth order puzzle.  

PubMed

Studies relating intellectual performance to birth order report conflicting results, some finding intellectual scores to increase, others to decrease with birth order. In contrast, the relationship between intellectual performance and family size is stable and consistently replicable. Why do these two highly related variables generate such divergent results? This birth order puzzle is resolved by means of the confluence model that quantifies the influences upon intellectual growth arising within the family context. At the time of a new birth, two opposing influences act upon intellectual growth of the elder sibling: (a) his or her intellectual environment is "diluted" and (b) he or she loses the "last-born's handicap" and begins serving as an intellectual resource to the younger sibling. Since these opposite effects are not equal in magnitude, the differences in intellectual performance among birth ranks are shown to be age dependent. While elder children may surpass their younger siblings in intellectual performance at some ages, they may be overtaken by them at others. Thus when age is taken into consideration, the birth order literature loses its chaotic character and an orderly pattern of results emerges. PMID:501518

Zajonc, R B; Markus, H; Markus, G B

1979-08-01

280

Replacive ordering in alloys  

NASA Astrophysics Data System (ADS)

Replacive ordering can occur in an alloy in a continuous mode by the development and amplification of concentration waves of appropriate wave vectors, k. Such processes known as spinodal clustering ( k?<0 0 0>) and spinodal ordering ( k defining the relevant superlattice structure) become operative when the alloy system experiences a free energy instability with respect to the order parameter associated with the corresponding wave vector. The presence of instabilities associated with these processes has been investigated in the Al-Li system using the cluster variation approach (CVM) considering upto the octahedron-tetrahedron cluster. The interaction energy parameters were obtained from the local density based first-principles band structure calculations. Predicted instability regimes have been compared with those obtained experimentally. The development of different competing superlattice structures in the Ni-Mo system has been discussed in terms of the development of appropriate concentration waves. Free energy-order parameter plots for different k-vectors have been compared for predicting relative stabilities of these superstructures and the evolutionary path of the ordering process. These results have been shown to be consistent with the experimental findings on this system.

Banerjee, S.; Arya, A.; Das, G. P.

1999-08-01

281

Birth Order and Psychopathology  

PubMed Central

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.

Risal, Ajay; Tharoor, Hema

2012-01-01

282

Order, topology and preference  

NASA Technical Reports Server (NTRS)

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.

Sertel, M. R.

1971-01-01

283

Comparing and Ordering Fractions  

NSDL National Science Digital Library

Use area models to compare and order fractions. Also see a visual representation of the least common denominator of two fractions. With the visual representation of the LCD, this Gizmo can be an introduction to adding and subtracting fractions with unlike denominators.

2007-12-12

284

Operation Order Algebra Game  

NSDL National Science Digital Library

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.

2012-01-01

285

The Birth Order Puzzle.  

ERIC Educational Resources Information Center

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)

Zajonc, R. B.; And Others

1979-01-01

286

Memory for Serial Order.  

ERIC Educational Resources Information Center

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

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

1989-01-01

287

Order of Operations Four  

NSDL National Science Digital Library

This game is similar to Connect Four! To earn a piece to place on the board, you must answer an order of operations question (addition / subtraction, multiplication / division, exponents, and parentheses). In this game, you can also choose the time limit, difficulty level, and type of questions.

2010-01-01

288

New World Order.  

National Technical Information Service (NTIS)

This study provides a point of view concerning many of the questions that one asks of himself upon hearing President Bush speak of New World Order and witnessing the successes of the coalition formed to enforce U.N. resolutions in the recent Gulf War. Suc...

S. S. Abid

1992-01-01

289

Ordered Families of Distributions  

Microsoft Academic Search

A comparison is made of several definitions of ordered sets of distributions, some of which were introduced earlier by the author [7], [8] and by Rubin [10]. These definitions attempt to make precise the intuitive notion that large values of the parameter which labels the distributions go together with large values of the random variables themselves. Of the various definitions

Erich L. Lehmann

1955-01-01

290

Birth Order Debate Resolved?  

ERIC Educational Resources Information Center

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…

Zajonc, R. B.

2001-01-01

291

Ordered oxynitride perovskites  

US Patent & Trademark Office Database

This invention relates to partially ordered and ordered oxynitride perovskites of the general formula ABO.sub.2N that are polar insulators. A comprises one or more cations or set of cations that sit in sites derived from the A-site in the perovskite structure. B comprises one or more cations or set of cations that sit in sites derived from the B-site in the perovskite structure. C comprises oxygen, O, with optionally some nitrogen, N, and D comprises N, with optionally some O. The total valence of the cations A+B is equal to the total valence of the anions 2 C+D. Also disclosed are methods of producing such oxynitride perovskites and uses of such oxynitride perovskites.

2014-05-13

292

Order patterns and chaos  

NASA Astrophysics Data System (ADS)

Chaotic maps can mimic random behavior in a quite impressive way. In particular, those possessing a generating partition can produce any symbolic sequence by properly choosing the initial state. We study in this Letter the ability of chaotic maps to generate order patterns and come to the conclusion that their performance in this respect falls short of expectations. This result reveals some basic limitation of a deterministic dynamic as compared to a random one. This being the case, we propose a non-statistical test based on ‘forbidden’ order patterns to discriminate chaotic from truly random time series with, in principle, arbitrarily high probability. Some relations with discrete chaos and chaotic cryptography are also discussed.

Amigó, José M.; Kocarev, Ljupco; Szczepanski, Janusz

2006-06-01

293

Second order symmetry operators  

NASA Astrophysics Data System (ADS)

Using systematic calculations in spinor language, we obtain simple descriptions of the second order symmetry operators for the conformal wave equation, the Dirac–Weyl equation and the Maxwell equation on a curved four-dimensional Lorentzian manifold. The conditions for existence of symmetry operators for the different equations are seen to be related. Computer algebra tools have been developed and used to systematically reduce the equations to a form which allows geometrical interpretation.

Andersson, Lars; Bäckdahl, Thomas; Blue, Pieter

2014-07-01

294

Higher order Josephson effects  

NASA Astrophysics Data System (ADS)

Gaussian linking of superconducting loops containing Josephson junctions with enclosed magnetic fields gives rise to interference shifts in the phase that modulates the current carried through the loop, proportional to the magnitude of the enclosed flux. We generalize these results to higher order linking of a superconducting loop with several magnetic solenoids, and show that there may be interference shifts proportional to the product of two or more fluxes.

Buniy, Roman V.; Kephart, Thomas W.

2010-06-01

295

Icosahedral order in liquids  

SciTech Connect

The possibility of icosahedral order in liquids and its role in glass transition is discussed in a broad context of statistical mechanics of liquid. It is pointed out that the structures of glasses and liquids are described both in terms of the topology of atomic bond networks as well as the local distortion of the atomic bonds. While topology plays a dominant role in covalent glasses, local distortion is likely to be more important for metallic glasses.

Egami, Takeshi [ORNL

2007-01-01

296

1.NBT Ordering Numbers  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Malik is given a list of numbers: 1 \\ \\ 5 \\ \\ 10 \\ \\ 50 \\ \\ 100 He wants to include the following numbers so all numbers will be listed in order from l...

297

On emerging nuclear order  

PubMed Central

Although the nonrandom nature of interphase chromosome arrangement is widely accepted, how nuclear organization relates to genomic function remains unclear. Nuclear subcompartments may play a role by offering rich microenvironments that regulate chromatin state and ensure optimal transcriptional efficiency. Technological advances now provide genome-wide and four-dimensional analyses, permitting global characterizations of nuclear order. These approaches will help uncover how seemingly separate nuclear processes may be coupled and aid in the effort to understand the role of nuclear organization in development and disease.

Rajapakse, Indika

2011-01-01

298

3.NF Ordering Fractions  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Arrange the fractions in order from least to greatest. Explain your answer with a picture. $\\frac{1}{5}, \\frac{1}{7}, \\frac{1}{3} $ $\\frac{2}{5}, \\frac...

299

Higher order Bezier circles  

NASA Technical Reports Server (NTRS)

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.

Chou, Jin

1993-01-01

300

Partially Ordered Models  

NASA Astrophysics Data System (ADS)

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.

Deveaux, Vincent; Fernández, Roberto

2010-11-01

301

Solid-state (127)I NMR and GIPAW DFT study of metal iodides and their hydrates: structure, symmetry, and higher-order quadrupole-induced effects.  

PubMed

Central-transition (127)I solid-state nuclear magnetic resonance (SSNMR) spectra are presented for several anhydrous group 2 metal iodides (MgI(2), CaI(2), SrI(2), and BaI(2)), hydrates (BaI(2)·2H(2)O and SrI(2)·6H(2)O), and CdI(2) (4H polytype). Variable offset cumulative spectrum data acquisition coupled with echo pulse sequences and an 'ultrahigh' applied field of 21.1 T were usually suitable to acquire high-quality spectra. Spectral analysis revealed iodine-127 nuclear quadrupole coupling constants (C(Q)((127)I)) ranging in magnitude from 43.5 (CaI(2)) to 214 MHz (one site in SrI(2)). For very large C(Q), analytical second-order perturbation theory could not be used to reliably extract chemical shifts and a treatment which includes quadrupolar effects exactly was required (Bain, A. D. Mol. Phys. 2003, 101, 3163). Differences between second-order and exact modeling allowed us to observe 'higher-order' quadrupole-induced effects for the first time. This finding will have implications for the interpretation of SSNMR spectra of quadrupolar nuclei with large quadrupole moments. In favorable situations (i.e., C(Q)((127)I) < 120 MHz), measurements were also performed at 11.75 T which when combined with the 21.1 T data allowed us to measure iodine chemical shift (CS) tensor spans in the range from 60 (BaI(2)·2H(2)O) to 300 ppm (one site in BaI(2)). These measurements represent the first complete characterizations (i.e., electric field gradient and CS tensors as well as their relative orientation) of noncubic iodide sites using (127)I SSNMR. In select cases, the SSNMR data are supported with (127)I NQR measurements. We also summarize a variety of trends in the halogen SSNMR parameters for group 2 metal halides. Gauge-including projector-augmented wave DFT computations are employed to complement the experimental observations, to predict potential structures for the two hydrates, and to highlight the sensitivity of C(Q)((127)I) to minute structural changes, which has potential applications in NMR crystallography. PMID:20860347

Widdifield, Cory M; Bryce, David L

2010-10-14

302

Computerized Physician Order Entry  

PubMed Central

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

Khanna, Raman; Yen, Tony

2014-01-01

303

Order in spontaneous behavior.  

PubMed

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

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

2007-01-01

304

Order in Spontaneous Behavior  

PubMed Central

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

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

2007-01-01

305

Ordered operator expansions and reconstruction from ordered moments  

NASA Astrophysics Data System (ADS)

The structure of ordered expansions in powers of boson operators and of canonical operators and the dual problem of operator reconstruction from ordered moments is derived and applied to the complete Gaussian class of ordering. In particular, the interpolation lines between normal and antinormal ordering and between standard and antistandard ordering with Weyl symmetrical ordering in their centre are dealt with in detail. The auxiliary operators for expansions in symmetrical ordering are explicitly found in the Fock-state representation and in other different representations. General and specialized formulae are derived for different ordering of powers of linear combinations of boson and of canonical operators which involve Hermite polynomials of operators. The link between symmetrical ordering of powers of boson operators and of canonical operators is expressed by means of Jacobi polynomials. Some basic formulae of operator ordering and operator expansion are collected for convenient use in the appendix. Keywords: Ordered operator expansions

Wünsche, Alfred

1999-04-01

306

Order Statistics and Robust Inference.  

National Technical Information Service (NTIS)

This paper falls under two headings: Order Statistics and Nonparametric Statistics. Topics investigated include the following: robustness and estimation in the presence of outliers; inequalities for order statistics and functions of order statistics; movi...

R. A. David

1988-01-01

307

Order Dimension, Strong Bruhat Order and Lattice Properties for Posets  

Microsoft Academic Search

We determine the order dimension of the strong Bruhat order on flnite Coxeter groups of types A, B and H. The order dimension is determined using a generalization of a theorem of Dilworth: dim(P) = width(Irr(P)), whenever P satisfles a simple order-theoretic condition called here the dissec- tive property (or \\\\clivage\\

Nathan Reading

2002-01-01

308

Ordered operator expansions and reconstruction from ordered moments  

NASA Astrophysics Data System (ADS)

The structure of ordered expansions in powers of boson operators and of canonical operators and the dual problem of operator reconstruction from ordered moments is derived and applied to the complete Gaussian class of ordering. In particular, the interpolation lines between normal and antinormal ordering and between standard and antistandard ordering with Weyl symmetrical ordering in their centre are dealt with in detail. The auxiliary operators for expansions in symmetrical ordering are explicitly found in the Fock-state representation and in other different representations. General and specialized formulae are derived for different ordering of powers of linear combinations of boson and of canonical operators which involve Hermite polynomials of operators. The link between symmetrical ordering of powers of boson operators and of canonical operators is expressed by means of Jacobi polynomials. Some basic formulae of operator ordering and operator expansion are collected for convenient use in the appendix.

Wünsche, Alfred

1999-04-01

309

Signatures of hidden-order symmetry in torque oscillations, elastic constant anomalies, and field-induced moments in URu2Si2  

NASA Astrophysics Data System (ADS)

We discuss the conclusions on the symmetry of hidden order (HO) in URu2Si2 that may be drawn from recent torque experiments in a rotating magnetic field by Okazaki [Science0036-807510.1126/science.1197358 331, 439 (2011)] (to be published). They are very sensitive to changes in the magnetic susceptibility induced by HO. We show that the observed twofold angular torque oscillations give evidence that HO has degenerate E-type (yz, zx) symmetry where both components are realized. The oscillations have the wrong characteristics or are absent for the one-dimensional (1D) nontrivial representations like quadrupolar B1(x2-y2) and B2(xy) type HO or hexadecapolar A2[xy(x2-y2)] type HO. Therefore, they may be excluded as candidates for HO. We also predict the field-angular variation of possible field-induced Bragg peaks based on the underlying E-type order parameter and discuss the expected elastic constant anomalies.

Thalmeier, Peter; Takimoto, Tetsuya

2011-04-01

310

Topology in Ordered Phases  

NASA Astrophysics Data System (ADS)

I. Topology as universal concept. Optical vorticulture / M. V. Berry. On universality of mathematical structure in nature: topology / T. Matsuyama. Topology in physics / R. Jackiw. Isoholonomic problem and holonomic quantum computation / S. Tanimura -- II. Topological crystals. Topological crystals of NbSe[symbol] / S. Tanda ... [et al.]. Superconducting states on a Möbius strip / M. Hayashi ... [et al.]. Structure analyses of topological crystals using synchrotron radiation / Y. Nogami ... [et al.]. Transport measurement for topological charge density waves / T. Matsuura ... [et al.]. Theoretical study on Little-Parks oscillation in nanoscale superconducting ring / T. Suzuki, M. Hayashi and H. Ebisawa. Frustrated CDW states in topological crystals / K. Kuboki ... [et al.]. Law of growth in topological crystal / M. Tsubota ... [et al.]. Synthesis and electric properties of NbS[symbol]: possibility of room temperature charge density wave devices / H. Nobukane ... [et al.]. How does a single crystal become a Möbius strip? / T. Matsuura ... [et al.]. Development of X-ray analysis method for topological crystals / K. Yamamoto ... [et al.] -- III. Topological materials. Femtosecond-timescale structure dynamics in complex materials: the case of (NbSe[symbol])[symbol]I / D. Dvorsek and D. Mihailovic. Ultrafast dynamics of charge-density-wave in topological crystals / K. Shimatake ... [et al.]. Topology in morphologies of a folded single-chain polymer / Y. Takenaka, D. Baigl and K. Yoshikawa. One to two-dimensional conversion in topological crystals / T. Toshima, K. Inagaki and S. Tanda. Topological change of Fermi surface in Bismuth under high pressure / M. Kasami ... [et al.]. Topological change of 4, 4'-bis[9-dicarbazolyl]-2, 2'-biphenyl (CBP) by international rearrangement / K. S. Son ... [et al.]. Spin dynamics in Heisenberg triangular system VI5 cluster studied by [symbol]H-NMR / Y. Furukawa ... [et al.]. STM/STS on NbSe[symbol] nanotubes / K. Ichimura ...[et al.]. Nanofibers of hydrogen storage alloy / I. Saita ... [et al.]. Synthesis of stable icosahedral quasicrystals in Zn-Sc based alloys and their magnetic properties / S. Kashimoto and T. Ishimasa. One-armed spiral wave excited by eam pressure in accretion disks in Be/X-Ray binaries / K. Hayasaki and A. T. Okazaki -- IV. Topological defects and excitations. Topological excitations in the ground state of charge density wave systems / P. Monceau. Soliton transport in nanoscale charge-density-wave systems / K. Inagaki, T. Toshima and S. Tanda. Topological defects in triplet superconductors UPt3, Sr[symbol]RuO[symbol], etc. / K. Maki ... [et al.]. Microscopic structure of vortices in type II superconductors / K. Machida ... [et al.]. Microscopic neutron investigation of the Abrikosov state of high-temperature superconductors / J. Mesot. Energy dissipation at nano-scale topological defects of high-Tc superconductors: microwave study / A. Maeda. Pressure induced topological phase transition in the heavy Fermion compound CeAl[symbol] / H. Miyagawa ... [et al.]. Explanation for the unusual orientation of LSCO square vortex lattice in terms of nodal superconductivity / M. Oda. Local electronic states in Bi[symbol]Sr[symbol]CaCu[symbol]O[symbol] / A. Hashimoto ... [et al.] -- V. Topology in quantum phenomena. Topological vortex formation in a Bose-Einstein condensate of alkali-metal atoms / M. Nakahara. Quantum phase transition of [symbol]He confined in nano-porous media / K. Shirahama, K. Yamamoto and Y. Shibayama. A new mean-field theory for Bose-Einstein condensates / T. Kita. Spin current in topological cristals / Y. Asano. Antiferromagnetic defects in non-magnetic hidden order of the heavy-electron system URu[symbol]Si[symbol] / H. Amitsuka, K. Tenya and M. Yokoyama. Magnetic-field dependences of thermodynamic quantities in the vortex state of Type-II superconductors / K. Watanabe, T. Kita and M. Arai. Three-magnon-mediated nuclear spin relaxation in quantum ferrimagnets of topological origin / H. Hori and S, Yamamoto. Topological aspects of wave function statistics at t

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

2006-08-01

311

Orderly Spanning Trees with Applications  

Microsoft Academic Search

We introduce and study orderly spanning trees of plane graphs. This algorithmic tool generalizes canonical orderings, which exist only for triconnected plane graphs. Although not every plane graph admits an orderly spanning tree, we provide an algorithm to compute an orderly pair for any connected planar graph G, consisting of an embedded planar graph H isomorphic to G, and an

Yi-Ting Chiang; Ching-Chi Lin; Hsueh-I Lu

2001-01-01

312

Ordering Genetic Algorithms and Deception  

Microsoft Academic Search

This paper considers deception in the context of ordering genetic algorithms (GAs). Order-four deceptive ordering problems are designed for absolute and relative ordering decoding. Three different crossover operators are used in both absolute and relative or- dering problems, and for each combination of crossover operator and coding, the schema survival probability is calculated. Simulation results show that no single crossover

Hillol Kargupta; Kalyanmoy Deb; David E. Goldberg

1992-01-01

313

Connection of Partial Order Logics and Partial Order Reduction Methods.  

National Technical Information Service (NTIS)

The authors examine the connection between 'equivalence robust' subsets of propositional temporal logics (LTL and CTL(star)), for which partial order reduction methods can be applied in model checking, and partial order logics and equivalences. For the li...

P. Niebert W. Penczek

1995-01-01

314

Partial Orders of Dimension 2, Interval Orders and Interval Graphs.  

National Technical Information Service (NTIS)

The paper has two main purposes. The first is to illustrate the relationship among dimensionality and several other concepts of interest in the theory of binary relations, including weak orders, interval orders, semiorders, interval graphs, comparability ...

F. S. Roberts K. A. Baker P. C. Fishburn

1970-01-01

315

Second-Order Algebraic Theories  

NASA Astrophysics Data System (ADS)

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

Fiore, Marcelo; Mahmoud, Ola

316

Deuterium Spin Probes of Backbone Order in Proteins: A 2H NMR Relaxation Study of Deuterated Carbon ? Sites  

PubMed Central

2H spin relaxation NMR experiments to study the dynamics of deuterated backbone ?-positions, D?, are developed. To date, solution-state 2H relaxation measurements in proteins have been confined to side-chain deuterons - primarily 13CH2D or 13CHD2 methyl groups. It is shown that quantification of 2H relaxation rates at D? backbone positions and the derivation of associated order parameters of C?-D? bond vector motions in small [U-15N,13C,2H]-labeled proteins is feasible with reasonable accuracy. The utility of the developed methodology is demonstrated on a pair of proteins - ubiquitin (8.5 kDa) at 10°C, 27°C, and 40°C, and a variant of GB1 (6.5 kDa) at 22°C. In both proteins, the D?-derived parameters of the global rotational diffusion tensor are in good agreement with those obtained from 15N relaxation rates. Semi-quantitative solution state NMR measurements yield an average value of the quadrupolar coupling constant, QCC, for D? sites in proteins equal to 174 kHz. Using the uniform value of QCC for all D? sites, we show that C?-D? bond vectors are motionally distinct from the backbone amide N-H bond vectors, with 2H-derived squared order parameters of C?-D? bond vector motions, S2 C?D?, on average slightly higher than their N-H amides counterparts, S2 NH. For ubiquitin, the 2H-derived backbone mobility compares well with that found in a 1-?s molecular dynamics simulation.

Sheppard, Devon; Li, Da-Wei; Bruschweiler, Rafael; Tugarinov, Vitali

2009-01-01

317

Birth Order and the Aviator.  

National Technical Information Service (NTIS)

This report conducts limited exploratory research into the possible relationship between birth order and an above average aptitude for aviation training. It reviews some of the basic elements of the science of ethology, birth order traits and possible cor...

B. C. Hertsgaard

1987-01-01

318

Diffusion Processes in Ordered Alloys.  

National Technical Information Service (NTIS)

This monograph describes the problem of ordering and diffusion in intermetallic phases. The theory of ordering is examined in complex systems characterized by more than one degree of long-range order. The monograph presents the results of studies on the k...

L. N. Larikov V. V. Geichenko V. M. Fal'chenko

1981-01-01

319

Definability in the Subword Order  

NASA Astrophysics Data System (ADS)

We develop a theory of (first-order) definability in the subword partial order in parallel with similar theories for the h-quasiorder of finite k-labeled forests and for the infix order. In particular, any element is definable (provided that words of length 1 or 2 are taken as parameters), the first-order theory of the structure is atomic and computably isomorphic to the first-order arithmetic. We also characterize the automorphism group of the structure and show that any arithmetical predicate invariant under the automorphisms of the structure is definable in the structure.

Kudinov, Oleg V.; Selivanov, Victor L.; Yartseva, Lyudmila V.

320

Ordered Delinquency: The "Effects" of Birth Order On Delinquency  

PubMed Central

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.

Cundiff, Patrick R.

2014-01-01

321

Ordered delinquency: the "effects" of birth order on delinquency.  

PubMed

Juvenile delinquency has long been associated with birth order in popular culture. While images of the middle child acting out for attention or the rebellious youngest child readily spring to mind, little research has attempted to explain why. Drawing from Adlerian birth order theory and Sulloway's born-to-rebel hypothesis, I examine the relationship between birth order and a variety of delinquent outcomes during adolescence. Following some recent research on birth order and intelligence, I use new methods that allow for the examination of between-individual and within-family differences to better address the potential spurious relationship. My findings suggest that contrary to popular belief, the relationship between birth order and delinquency is spurious. Specifically, I find that birth order effects on delinquency are spurious and largely products of the analytic methods used in previous tests of the relationship. The implications of this finding are discussed. PMID:23719623

Cundiff, Patrick R

2013-08-01

322

Birth order among homosexual men.  

PubMed

Nicolosi and Byrd in 2002 summarized empirical research on birth order and sexual orientation in men, which research has documented that homosexual men have a later birth order than heterosexual men. They did not, however, note a more refined analysis of an earlier null finding by Siegelman. This 1998 reanalysis by Blanchard, Zucker, Siegelman, Dickey, and Klassen also confirmed the later birth order of homosexual men. PMID:12674268

Zucker, Kenneth J; Blanchard, Ray; Siegelman, Marvin

2003-02-01

323

Prerequisites for chiral charge order  

NASA Astrophysics Data System (ADS)

The chiral charge density wave state which was recently discovered in TiSe2 can be understood as a combination of orbital and charge order. Here, we discuss the prerequisite material properties for this type of chiral charge order to emerge. We find that although both the lattice and orbital structure constrain the set of candidate materials, there remains a class of materials in which chiral charge order is expected to emerge.

van Wezel, Jasper

2012-06-01

324

Birth order and social behavior  

Microsoft Academic Search

Recent research of Schachter has redirected a longstanding interest in physiological, psychological, and sociological correlates of order of birth to affiliative or withdrawal tendencies as birth-order correlates. The most firmly established and persistent finding relative to birth order shows an overproportion of 1st-born children in college. Substantial evidence also exists showing (1) 1st-born to be more susceptible than later born

Jonathan R. Warren

1966-01-01

325

Ordered shapes in nonequilibrium growth  

Microsoft Academic Search

Patterns observed during nonequilibrium growth display complex ordering on many length scales. We focus on ordered patterns which reflect the interplay of microscopic and macroscopic dynamics. The fundamental morphologies which result, and which are the building blocks of more complex patterns, include dendritic and tip-splitting growth. The latter gives rise to the two- dimensional dense-branching morphology (DBM). We review the

Eshel Ben-Jacob; Peter Garik

1989-01-01

326

Commonalities in the order book  

Microsoft Academic Search

This paper uses data from one of the most important European stock markets and shows that, in line with predictions from theoretical market microstructure, a small number of latent factors captures most of the variation in stock specific order books. We show that these order book commonalities are much stronger than liquidity commonality across stocks. The result that bid and

Helena Beltran-Lopez; Pierre Giot; Joachim Grammig

2006-01-01

327

Automated ordering of fingerprinted clones  

Microsoft Academic Search

Motivation: A considerable amount of human intervention is currently required to produce high-quality fingerprint-based physical maps for genomic studies. Results: An algorithm has been developed and imple- mented to automatically order fingerprinted clones within con- tigs. The resulting software, named CORAL (Clone ORdering ALgorithm), has been tested on maps that have previously been manually edited and on maps derived from

Stephane Flibotte; Readman Chiu; Chris Fjell; Martin Krzywinski; Jacqueline E. Schein; Heesun Shin; Marco A. Marra

2004-01-01

328

Magic Square of Fifth Order  

Microsoft Academic Search

I VENTURE to send you what I believe to be a very rare magic square of fifth order. Although there are more than 260,000 bordered squares of fifth order with the number 13 in the centre of the square, it seems a very rare thing indeed for any other number than 13 to be in the centre. I have not

J. C. Burnett

1930-01-01

329

Spearman Rank Order Correlation Coefficient  

NSDL National Science Digital Library

This page will calculate r_s , the Spearman rank- order correlation coefficient, for a bivariate set of paired XY rankings. As the page opens, you will be prompted to enter the number of items for which there are paired rankings. If you are starting out with raw (unranked) data, the necessary rank-ordering will be performed automatically.

Lowry, Richard, 1940-

2008-06-25

330

Ordering Sentences According to Topicality  

Microsoft Academic Search

This paper addresses the problem of find- ing or producing the best ordering of the sentences in a text. I focus on using se- mantic properties of the words, as well as the high-level structure of each of the texts, to produce or choose the best order- ing. In choosing an original sentence or- dering from a group of sentential

Ilana Bromberg

331

Ordered mesoporous materials in catalysis  

Microsoft Academic Search

Ordered mesoporous catalysts could open the door for new catalytic processes, based partly on novel principles, owing to their hitherto unprecedented intrinsic features. For the preparation of ordered mesoporous catalysts, many strategies have been described. These strategies and the essential properties of the resulting materials are described in the first part of this review. Catalytic processes over such mesoporous materials,

Akira Taguchi; Ferdi Schüth

2005-01-01

332

Introduction to Order of Operations  

NSDL National Science Digital Library

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.

2010-01-01

333

Birth Order: Reconciling Conflicting Effects.  

ERIC Educational Resources Information Center

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…

Zajonc, Robert B.; Mullally, Patricia R.

1997-01-01

334

Local structural orders in nanostructured Al2O3 prepared by high-energy ball milling  

Microsoft Academic Search

Nanostructured Al2O3 powders were prepared by high-energy ball milling of corundum. Both the solid state nuclear magnetic resonance spectra of the Al3+ ions and the solid state electron paramagnetic resonance spectra of incorporated Fe3+ ions are governed by noticeable spectral changes dependent on the duration of the mechanical treatment. The quadrupolar parameters of the 27Al nuclei and the zero-field splitting

G. Scholz; R. Stösser; J. Klein; G. Silly; J. Y. Buzaré; Y. Laligant; B. Ziemer

2002-01-01

335

Complex higher order derivative theories  

SciTech Connect

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.

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

336

Multiple order common path spectrometer  

NASA Technical Reports Server (NTRS)

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.

Newbury, Amy B. (Inventor)

2010-01-01

337

Higher Order Languages for Robots,  

National Technical Information Service (NTIS)

This state of the art review of higher order languages for robots provides a background of robot programming approaches. Strengths and weaknesses of various approaches are presented. The second section of the report discusses specific languages. Manipulat...

J. R. Blaha J. P. Lamoureux K. E. McKee

1986-01-01

338

Heavy electrons: Sleuthing hidden order  

Microsoft Academic Search

Physicists have long debated whether the 'hidden order' in URu2Si2 is itinerant or localized, and it remains inaccessible to direct external probes. The observation of an overdamped collective mode seems to resolve this outstanding issue.

V. Tripathi; P. Chandra; P. Coleman

2007-01-01

339

First-Order Net Systems.  

National Technical Information Service (NTIS)

There is a net theoretical system model called Predicate Transition Nets that describes distributed systems as dynamic first-order structures. The note demonstrates that predicate transition nets can be formulated in a straightforward fashion as special k...

H. J. Genrich K. Voss P. S. Thiagarajan

1990-01-01

340

Bone mineralization: Water brings order  

NASA Astrophysics Data System (ADS)

Measurements of the structure and organization of intact bone samples show that water plays a significant role in orienting bone apatite crystals, and that such ordering is mediated by an amorphous mineral coating layer.

Duer, Melinda; Veis, Arthur

2013-12-01

341

Reduced order adaptive controller studies  

NASA Technical Reports Server (NTRS)

The use of a reduced-order adaptive controller, can arise from a desire to reduce control complexity with a commensurate reduction in controller sensitivity or from necessity in an attempt to use a finite dimensional controller on an infinite dimensional system. An interest in developing adaptive controllers for flexible structures by application of existing lumped-parameter system (LPS) adaptive controller strategies to truncated expansion descriptions of the distributed parameter system (DPS) behavior of flexible structures has led to two qualitative descriptions of the misbehavior of reduced-order adaptive controllers. A summary is provided of these interpretations of the additional difficulties facing reduced-order adaptive controllers, which are bypassed by exact-order adaptive controllers. A test problem, which initializes attempts to quantify the qualitative insights, is also formulated.

Johnson, C. R., Jr.; Balas, M. J.

1980-01-01

342

Cation Ordering in Layered Nickelates  

NASA Astrophysics Data System (ADS)

The single layer Ruddlesden-Popper nickelates present a model system to understand how the effects of digital dopant cation ordering may affect the properties of 2-dimensional conducting sheets. We investigate the effects of aliovalent A-site cation order on LaSrNiO4 films. Using molecular beam epitaxy, we interleave full layers of SrO and LaO in a series of chemically equivalent films, varying the pattern of SrO and LaO layers relative to the NiO2 layers. Through synchrotron surface x-ray diffraction and Coherant Bragg Rod Analysis (COBRA), we directly investigate the A-site cation order and the resulting atomic displacements for each ordering pattern. We correlate these results with theoretical calculations and transport measurements of the layered nickelate films.

Nelson-Cheeseman, Brittany; Zhou, Hua; Cammarata, Antonio; Hoffman, Jason; Balachandran, Prasanna; Rondinelli, James; Bhattacharya, Anand

2013-03-01

343

Supersymmetric fifth order evolution equations  

SciTech Connect

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.

Tian, K. [LSEC, ICMSEC, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China) and Graduate School of Chinese Academy of Sciences, Beijing (China); Liu, Q. P. [Department of Mathematics, China University of Mining and Technology, Beijing 100083 (China)

2010-03-08

344

Hydrogels with the ordered structures  

Microsoft Academic Search

A water-swollen hydrogel with a molecularly-ordered structure was prepared by copolymerizing acrylic acid and acrylic monomer containing hydrophobic long alkyl or mesogenic moiety. The gels with a long alkyl side chain formed the crystalline structure and undergo the reversible order–disorder transition with change in temperature or solvent composition which accompanied a dramatic change in Young's modulus. These gels exhibited such

T. Miyazaki; K Yamaoka; T Kaneko; J. P Gong; Y Osada

2000-01-01

345

John F. Kennedy Executive Orders  

NSDL National Science Digital Library

The 214 Executive Orders signed by the 35th President have been scanned and converted to HTML by Maria E. Schieda of the University of Michigan School of Information. These include the orders to establish the Peace Corps (E.O. 10924), to establish the President's Committee on Equal Employment (E.O. 10925), and emergency instructions to government agencies during the Cuban Missile Crisis (E.O. 11051, 11058, 11087-11095). The collection is indexed by date, keyword, number, and title.

Kennedy, John F. (John Fitzgerald), 1917-1963.

1997-01-01

346

Birth Order, Schooling, and Earnings  

Microsoft Academic Search

Birth-order effects are posited by many to affect earnings and schooling. The authors show how such effects can be interpreted to shift either the earnings possibility frontier for siblings or parental preferences. The authors find empirical evidence for birth- order effects on (age-adjusted) schooling and on earnings for young U.S. adults, though the latter is not robust for all specifications.

Jere R. Behrman; Paul Taubman

1986-01-01

347

Ordered and chaotic Bohmian trajectories  

NASA Astrophysics Data System (ADS)

We discuss the issue of ordered and chaotic trajectories in the Bohmian approach of Quantum Mechanics from points of view relevant to the methods of Celestial Mechanics. The Bohmian approach gives the same results as the orthodox (Copenhagen) approach, but it considers also underlying trajectories guided by the wave. The Bohmian trajectories are rather different from the corresponding classical trajectories. We give examples of a classical chaotic system that is ordered quantum-mechanically and of a classically ordered system that is mostly chaotic quantum mechanically. Then we consider quantum periodic orbits and ordered orbits, that can be represented by formal series of the “third integral” type, and we study their asymptotic properties leading to estimates of exponential stability. Such orbits do not approach the “nodal points” where the wavefunction ? vanishes. On the other hand, when an orbit comes close to a nodal point, chaos is generated in the neighborhood of a hyperbolic point (called X-point). The generation of chaos is maximum when the X-point is close to the nodal point. Finally we remark that high order periodic orbits may behave as “effectively ordered” or “effectively chaotic” for long times before reaching the period.

Contopoulos, George; Efthymiopoulos, Christos

2008-09-01

348

On charge and orbital ordering  

NASA Astrophysics Data System (ADS)

In recent times there has been a resurgence of interest in the properties of transition metal oxides because of the wide range of physical properties that they exhibit. Recent developments in experimental techniques offer a direct probe to the novel types of ordering realised in these systems. Using first principle band structure calculations, we have critically examined^1 the results of resonant x-ray scattering experiments which are believed to directly probe charge and orbital ordering. Considering the specific case of La_0.5Sr_1.5MnO_4, we show that this technique actually probes most directly and sensitively small structural distortions in the system. Such distortions, often difficult to detect with more conventional techniques, invariably accompany and usually cause the orbital and charge orderings. In this sense, this technique is only an indirect probe of such types of ordering. Our results also provide a microscopic explanation of the novel types of charge and orbital ordering realized in this system and other doped manganites. 1. Priya Mahadevan, K. Terakura and D.D. Sarma, Phys. Rev. Lett. 87, 066404 (2001).

Mahadevan, Priya; Terakura, K.; Sarma, Dd

2002-03-01

349

Remembering and constructing an order.  

PubMed

The purpose of this study was to determine whether children who could recognize a linear order would be able to use this recognition to answer new questions about the linear order. Three-, 4-, 5-, and 6-year-old children were trained to choose a series over a nonseries, a series over a series ordered in the opposite direction, or one nonseries over another nonseries. They were also given a standard seriation task. Children could recognize a series before being able to construct one, but recognition of a series was not correlated with construction of a series. Although children did not use the linear order to construct a series, they could use it to make choices between two similar stimuli, only one of which contained a feature identical to the linear order. The comparison between seriation and recognition of one nonseries over another revealed that performance on these two tasks was correlated and that one common feature between them was systematicity, which occurred either in searching for relationships or constructing them. PMID:3437271

Blevins-Knabe, B

1987-12-01

350

DNR Orders and School Responsibility.  

ERIC Educational Resources Information Center

This paper discusses the legal and ethical questions surrounding "Do Not Resuscitate" (DNR) orders in the school environment. It begins by reviewing federal and state case law that addresses the appropriateness of medical services and the responsibility of schools in terms of provision of medical services. The review finds that when medical-like…

Sewall, Angela Maynard; Balkman, Kathy

351

Magnetic order in crocidolite asbestos  

Microsoft Academic Search

Magnetic properties of two samples of crocidolite (blue asbestos) have been examined using susceptibility and magnetization measurements, neutron diffraction, and Mössbauer spectroscopy. Both samples order magnetically at 30±1 K with a structure in which iron ions in the ribbons parallel to c are all coupled ferromagnetically but the moments of adjacent ribbons are oppositely aligned. The iron moments are oriented

A. Moukarika; J. M. D. Coey; N. V. Dang

1983-01-01

352

Peacekeeping. Perspectives in World Order.  

ERIC Educational Resources Information Center

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,…

Fraenkel, Jack R., Ed.; And Others

353

Macrojunctions ordering in polyelectrolyte hydrogels  

NASA Astrophysics Data System (ADS)

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.

Török, Gy; Lebedev, V. T.; Cser, L.; Buyanov, A. L.; Revelskaya, L. G.

2000-03-01

354

NCI Mouse Repository - Ordering Information  

Cancer.gov

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.

355

Bootstrapping the order selection test  

Microsoft Academic Search

We consider bootstrap versions of the order selection test of Eubank and Hart and Kuchibhatla and Hart for testing lack-of-fit of regression models. For homoscedastic data, conditions are established under which the bootstrap level error is smaller (asymptotically) than that of the large sample test A new statistic is proposed to deal with the case of heteroscedastic data. The limiting

Chien-Feng Chen; Jeffrey D. Hart; Suojin Wang

2001-01-01

356

Order estimation of Markov chains  

Microsoft Academic Search

We describe estimatorsn(X0,X1,...,Xn), which when applied to an unknown stationary process taking values from a countable al- phabet X, converge almost surely to k in case the process is a k-th order Markov chain and to infinity otherwise.

Gusztáv Morvai; Benjamin Weiss

2005-01-01

357

Birth order and intellectual development  

Microsoft Academic Search

Describes a confluence model that explains the effects of birth order and family size on intelligence. Intellectual development within the family context is conceived of as depending on the cumulative effects of the intellectual environment, which consists primarily of the siblings' and parents' intelligence. Mutual influences, through time, on the intellectual development of the siblings are described by the growth

R. B. Zajonc; Gregory B. Markus

1975-01-01

358

PEMDAS: Algebraic Order of Operations  

NSDL National Science Digital Library

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.

2009-03-15

359

Proving termination with Multiset Orderings  

Microsoft Academic Search

A common tool for proving the termination of programs is the well-founded set, a set ordered in such a way as to admit no infinite descending sequences. The basic approach is to find a termination function that maps the values of the program variables into some well-founded set, such that the value of the termination function is continually reduced throughout

Nachum Dershowitz I; Zohar Manna

1979-01-01

360

Moral Order and the Humanities.  

ERIC Educational Resources Information Center

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)

Howard, Thomas

1980-01-01

361

Proving Partial Order Liveness Properties  

Microsoft Academic Search

A temporal verification method which is based upon partial order semantics of traces [31] is presented. The semantic model used here can express the distributed nature of a program. E.g., properties such as serializability of database transactions, layering of a program, snapshots or the parallel execution of program segments.

Doron Peled; Amir Pnueli

1990-01-01

362

Strong hypergroups of order three  

Microsoft Academic Search

This paper investigates the question of when a finite hypergroup with three elements is strong, that is satisfies the condition that its dual signed hypergroup is actually a hypergroup. We classify hermitian hypergroups of order three by weight into two-dimensional families and show that the algebraic conditions arising from duality yield four interesting curves in the plane which bound the

N. J. Wildberger

2002-01-01

363

High Order Continuous Polugonal Patches  

Microsoft Academic Search

A polygonal patch method is described which can be used to fill a polygonal hole within a given k'th order continuous rectangular patch complex. The method is relatively easy to implement, since it only re- quires Ck extensions of the rectangular patch complex defined in terms of the rectangular patch parameterizations. The method is illustrated by reference to C2 bicubic

John A. Gregory; K. H. Lau

1992-01-01

364

Ultrastructure Processing of Ordered Polymers.  

National Technical Information Service (NTIS)

In order to explore the nonlinear elasticity of high-performance PBZT fibers, a method using laser-generated ultrasound has been developed to measure the Young's modulus of the fibers as a function of temperature and static tensile stress. X-ray diffracti...

R. K. Eby

1990-01-01

365

Relationship between spin ordering, entropy, and anomalous lattice variation in Mn3Sn(1-?)Si(?)C(1-?) compounds.  

PubMed

The crystal and magnetic structures of antiperovskite compounds Mn3SnC, Mn3Sn0.95C0.9, and Mn3Sn0.93Si0.07C0.94 were studied as a function of temperature and magnetic field by neutron powder diffraction. For Mn3SnC, the magnetic field induces a dramatic variation of antiferromagnetic moment and lattice parameter. Because of this spin-lattice coupling, the "square" antiferromagnetic (AFM) structure plays a key role in inducing a negative thermal expansion in the material. Moreover, the thermal expansion parameter is closely related to the rate of change of the AFM moment, which can be controlled by introducing vacancies or by doping. The variations of the AFM moment and lattice parameter in Mn3SnC with magnetic field make it possible to use the tunable properties for technical applications. PMID:24491172

Yan, Jun; Sun, Ying; Wen, Yongchun; Chu, Lihua; Wu, Meimei; Huang, Qingzhen; Wang, Cong; Lynn, Jeffrey W; Chen, Yunlin

2014-02-17

366

N.M.R. spectra of molecules containing quadrupolar nuclei  

Microsoft Academic Search

Information about N relaxation times and (N, F) coupling constants is obtained for three fluoropyridines from (a) a detailed band-shape analysis of the broad F resonance bands assigned to ortho-fluorine nuclei, (b) N resonance bands, and (c) N satellites in F resonance. The effects of medium and of temperature were investigated, and activation energies for rotational diffusion are given. Double

R. K. Harris; N. C. Pyper; R. E. Richards; G. W. Schulz

1970-01-01

367

Recent advances in ordered intermetallics  

SciTech Connect

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.

Liu, C.T.

1994-12-31

368

Antiferromagnetic order in amphibole asbestos  

Microsoft Academic Search

We have made magnetic susceptibility, electron spin resonance, and Mössbauer measurements on two different amphiboles, (Fe, Mg)7Si8O22(OH)2, and crocidolite, Na2Fe5Si8O22 (OH)2, which indicate that these materials are ordered antiferromagnetically at liquid helium temperatures. Amphibole minerals are characterized structurally by long double chains of linked silicate tetrahedra. The metal anions are 'sandwiched' between pairs of double silicate chains to form long

J. C. Eisenstein; M. F. Taragin; D. D. Thornton

1975-01-01

369

Antiferromagnetic order in amphibole asbestos  

Microsoft Academic Search

We have made magnetic susceptibility, electron spin resonance, and Mo¨ssbauer measurements on two different amphiboles, (Fe, Mg)7Si8O22(OH)2, and crocidolite, Na2Fe5Si8O22 (OH)2, which indicate that these materials are ordered antiferromagnetically at liquid helium temperatures. Amphibole minerals are characterized structurally by long double chains of linked silicate tetrahedra. The metal anions are ’sandwiched’ between pairs of double silicate chains to form long

J. C. Eisenstein; M. F. Taragin; D. D. Thornton

1975-01-01

370

Designing Fractional-order PI  

Microsoft Academic Search

Invasive weed optimization (IWO) has been found to be a simple but powerful algorithm for function optimization over continuous spaces. It has reportedly outperformed many types of evolutionary algorithms and other search heuristics when tested over both benchmark and real-world problems. This article describes the design of fractional-order proportional-integral-derivative (FOPID) controllers, using a newly developed variant of IWO, known as

Debarati Kundu; Kaushik Suresh; Swagatam Das; S. Ghosh

2009-01-01

371

Performances of order statistics CFAR  

Microsoft Academic Search

A previous analysis of order-statistics constant-false-alarm-rate (OS-CFAR) radar receiving a single pulse from a Rayleigh fluctuating target in a Rayleigh background is extended to a Rayleigh-plus-dominant target. The analysis includes effects of a multitarget environment. A detailed comparison of OS-CFAR, cell-averaging (CA) CFAR, and censored CA-CFAR is provided for a Rayleigh target in the presence of strongly interfering targets. The

Mordechai Shor; Nadav Levanon

1991-01-01

372

Highly ordered noncrystalline metallic phase.  

PubMed

We report the characterization of a unique metallic glass that, during rapid cooling of an Al-Fe-Si melt, forms by nucleation, followed by growth normal to a moving interface between the solid and melt with partitioning of the chemical elements. We determine experimentally that this is not a polycrystalline composite with nanometer-sized grains, and conclude that this may be a new kind of structure: an atomically ordered, isotropic, noncrystalline solid, possessing no long-range translational symmetry. PMID:23863012

Long, Gabrielle G; Chapman, Karena W; Chupas, Peter J; Bendersky, Leonid A; Levine, Lyle E; Mompiou, Frédéric; Stalick, Judith K; Cahn, John W

2013-07-01

373

Phylogenetic List of Insect Orders  

NSDL National Science Digital Library

from editor: this table doesn't have any link back to the webpage it is linked to, which puts the reader at a dead end and doesn't give the context of the parent site. They should just submit the parent webpage instead of the lists of terms and Orders separately. I already approved the .pdf list of terms, but we should consider just posting the parent site instead: http://entnemdept.ifas.ufl.edu/choate/insecpdf.htm.

0002-11-30

374

The social order of markets  

Microsoft Academic Search

In this article I develop a proposal for the theoretical vantage point of the sociology of markets, focusing on the problem\\u000a of the social order of markets. The initial premise is that markets are highly demanding arenas of social interaction, which\\u000a can only operate if three inevitable coordination problems are resolved. I define these coordination problems as the value problem,

Jens Beckert

2009-01-01

375

Torn Shirts Inc: Telephone Orders  

NSDL National Science Digital Library

A challenging but well-guided activity, Torn Shirts has students analyze data to reach a decision on a business question. They first determine the probability that a customer calling to order a shirt gets a busy signal, then estimate the amount of money the company might lose when customers get a busy signal. Work with graphs and averages, especially the median, helps students reach a conclusion.

Research, High S.; Chien, Ellen; Lawson, Marlene; Snyder, Helen

1996-01-01

376

Birth order, development and personality.  

PubMed

First borns tend to be different, some of the time, than children born into the other birth orders. This seems due to parental treatment. Parents are often overly anxious about their first child, and may be more restrictive with the first child than with later children. It may be that this is especially true if the first child is female, given the tendency of parents to be more protective of females than of males. Also, the first child has more time alone with the parents than subsequent children, by virtue of having no siblings until the second child is born. From the above factors, it appears that first borns grow up more fearful than later born children but also more intellectually oriented. These are only tendencies and would not be absolutely true in every instance. But, the birth order does seem to initiate a tendency for things to be as stated. As a result, first borns achieve much more than the other birth orders, perhaps due to early adult-oriented styles learned when they had only the parents and no other siblings. If this speculation is correct, the same finding should hold for only children as well. The greater anxiety, achievement, and creativity of some first borns means their lives may be very different as a result of having been the first born child in the family. PMID:1310365

Eisenman, R

1992-01-01

377

Charge ordering and intermediate range order in ammonium ionic liquids  

NASA Astrophysics Data System (ADS)

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.

Siqueira, Leonardo J. A.; Ribeiro, Mauro C. C.

2011-11-01

378

Ordering self-assembled nanostructures  

NASA Astrophysics Data System (ADS)

Many innovative applications of nanosciences, such as semiconductor lasers, quantum computing, information storage, quantum cryptography, and semiconductor transistors largely rely on the ability to fabricate long-range ordered nanostructures. However, conventional top-down techniques have mostly reached a bottleneck that thwarts the progress toward future miniaturization needed for the next generation of nanodevices. This constraint imposes the need to develop new manufacturing methods to engineering nanodevices on the single-digit-nanometer scale. Self-assembly, the spontaneous formation of regular arrays, is emerging as one of the most promising avenues for both miniaturization and fabrication. While self-assembly can bring us the direct large scale fabrication of nanostructures, the stochastic nature stemming from symmetry breaking bifurcation inhibits the full realization of ordered nano-arrays. Since the quality of electronic, optical, magnetic and photonic properties of nanodevices depends substantially on the uniformity of their arrangement, avoiding imperfections in self-assembly is important; thus forms the central subject of this dissertation. We propose a method for ordering self-assembled nanostructures by imposing control on the deposition using an opaque mask placed a finite distance above the substrate. This choice is motivated by studies of symmetry breaking, which suggest that boundary conditions provide a means to select among all possible broken symmetry states. We have conducted both linear and nonlinear stability analyses to derive optimal control parameters that support specific pattern formation. Numerical integrations of two morphological self-assembly models (2D biphasic surface islands in a monolayer and 3D epitaxial quantum dot growth in Stranski-Krastanow mode) show that the proposed method can indeed give large scale, well organized nanostructures.

Shi, Feng

379

Second order transport from anomalies  

NASA Astrophysics Data System (ADS)

We study parity odd transport at second order in derivative expansion for a non-conformal charged fluid. We see that there are 27 parity odd transport coefficients, of which 12 are non-vanishing in equilibrium. We use the equilibrium partition function method to express 7 of these in terms of the anomaly, shear viscosity, charge diffusivity and thermodynamic functions. The remaining 5 are constrained by 3 relations which also involve the anomaly. We derive Kubo formulae for 2 of the transport coefficients and show these agree with that derived from the equilibrium partition function.

Bhattacharyya, Sayantani; David, Justin R.; Thakur, Somyadip

2014-01-01

380

All Order Covariant Tubular Expansion  

NASA Astrophysics Data System (ADS)

We consider tubular neighborhood of an arbitrary submanifold embedded in a (pseudo-) Riemannian manifold. This can be described by Fermi normal coordinates (FNC) satisfying certain conditions as described by Florides and Synge in [15]. By generalizing the work of Muller et al. in [54] on Riemann normal coordinate expansion, we derive all order FNC expansion of vielbein in this neighborhood with closed form expressions for the curvature expansion coefficients. Our result is shown to be consistent with certain integral theorem for the metric proved in [15].

Mukhopadhyay, Partha

2014-11-01

381

Crystalline order on the paraboloid  

NASA Astrophysics Data System (ADS)

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.

Giomi, Luca; Bowick, Mark

2006-03-01

382

Topological order and reflection positivity  

NASA Astrophysics Data System (ADS)

The focus of this paper is twofold. First, we observe that Hamiltonians displaying both topological order and reflection positivity have an interesting property: expectations in different ground-state vectors of a given local operator WA have the same sign. Secondly, we illustrate this result with a specific Majorana Hamiltonian, related to the toric code which is widely studied in quantum information theory. We show that expectations of reflection-symmetric loops in ground states of this Hamiltonian are vortex-free or vortex-full.

Jaffe, Arthur; Pedrocchi, Fabio L.

2014-02-01

383

Superconductivity and Excitonic Charge Order  

NASA Astrophysics Data System (ADS)

It was suggested four decades ago that excitons as well as phonons could mediate superconductivity and that the temperature limits usually imposed by phonons could thus be avoided. In practice this form of excitonic pairing turned out to be elusive, because phonon softening typically causes a structural instability to occur before excitonic superconductivity has a chance to arise. Upon suppression of this CDW order however, superconductivity once again has an opportunity to materialise, as has recently been observed in for example pure TiSe2 under pressure. It is unclear what role is played by the excitons in such an environment of critical structural fluctuations, and whether they can have any effect on the pairing or indeed TC. Here we introduce a theoretical model to study the ways in which SC, CDW and excitonic order compete, coexist and even cooperate. Applying the model to TiSe2, we show that the hitherto elusive mechanism driving its CDW transition is a combination of excitonic and Jahn-Teller effects, and that under pressure it is likely to display an unusual type of superconductivity mediated by combinations of excitons and phonons.

van Wezel, Jasper; Nahai-Williamson, Paul; Saxena, Siddarth

2010-03-01

384

Biocatalytic induction of supramolecular order  

NASA Astrophysics Data System (ADS)

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.

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

385

Ordering Phenomena in Undercooled Alloys  

SciTech Connect

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].

Fultz, Brent

1997-07-17

386

Ordered structures and jet noise  

NASA Technical Reports Server (NTRS)

A series of measurements of near field pressures and turbulent velocity fluctuations were made in a jet having a Reynolds number of about 50,000 in order to investigate more quantitatively the character and behavior of the large scale structures, and to ascertain their importance to the jet noise problem. It was found that the process of interaction between vortices can be inhibited by artificially exciting the shear layers with periodic disturbances of certain frequency. The turbulent fluctuation amplitudes measured at four diameters downstream decreased considerably. Finally, it was observed that the passage frequency of the structures decreased with x in a similar manner as the frequency corresponding to the maximum intensity radiation emanating from the same value of x.

Petersen, R. A.; Kaplan, R. E.; Laufer, J.

1974-01-01

387

Thermodynamics of Intragenic Nucleosome Ordering  

NASA Astrophysics Data System (ADS)

The nucleosome ordering observed in vivo along yeast genes is described by a thermodynamical model of nonuniform fluid of 1D hard rods confined by two excluding energy barriers at gene extremities. For interbarrier distances L?1.5kbp, nucleosomes equilibrate into a crystal-like configuration with a nucleosome repeat length (NRL) L/ñ165bp, where n is the number of regularly positioned nucleosomes. We also observe “bistable” genes with a fuzzy chromatin resulting from a statistical mixing of two crystal states, one with an expanded chromatin (NRL ˜L/n) and the other with a compact one (NRL ˜L/(n+1)). By means of single nucleosome switching, bistable genes may drastically alter their expression level as suggested by their higher transcriptional plasticity. These results enlighten the role of the intragenic chromatin on gene expression regulation.

Chevereau, G.; Palmeira, L.; Thermes, C.; Arneodo, A.; Vaillant, C.

2009-10-01

388

Magnetic ordering in manganese clusters  

NASA Astrophysics Data System (ADS)

Isolated manganese clusters, Mnn,(n=5-22) are deflected by a linear-gradient magnetic field. Mn7-Mn22 are found to deflect uniformly toward high field. The magnitude of the deflections indicate susceptibilities far in excess of those expected based on the susceptibility of bulk manganese, demonstrating that Mn clusters in this size range are magnetically ordered. Per-atom moments obtained from Curie’s Law analysis range from 0.4?b(Mn19) to 1.7?b(Mn12) . For Mn5 and Mn6 , symmetric broadening of the cluster beam is observed, and their moments were determined via line-shape analysis using both free-spin and adiabatic rotor models. The measured moments, interpreted in light of recent density functional theory calculations, suggest that Mn clusters in this size range are molecular ferrimagnets.

Knickelbein, Mark B.

2004-07-01

389

Acyl chain conformational ordering of individual components in liquid-crystalline bilayers of mixtures of phosphatidylcholines and phosphatidic acids. A comparative FTIR and 2H NMR study  

NASA Astrophysics Data System (ADS)

The conformational ordering of the acyl chains of all possible binary 1:1 mixtures containing the phospholipids DMPC, DMPA, DPPC, and DPPA was investigated using FTIR and 2H NMR spectroscopy. One of the components was always labelled with perdeuterated chains to be able to observe the individual behaviour of the two components. From the temperature dependence of the frequencies of the symmetric and antisymmetric CH 2- and CD 2-stretching vibrations the transition temperatures were determined. The integral intensities of the conformation sensitive CH 2-wagging bands at ca. 1368 cm -1(gtg' and gtg sequences), 1356 cm -1 (double gauche), and 1342 cm -1 (end gauche) can be converted to numbers of gauche conformers per acyl chain using calibration factors published by Senak et al. J. Phys. Chem. 95 (1991) 2565. The 2H NMR quadrupolar splittings of the CD 2-segments of the perdeuterated lipid components are affected not only by trans-gauche isomerizations but also by long axis rotations and restricted wobbling motions of the acyl chains. The values of the average gauche probability overlinep3 from FTIR spectroscopy and the average order parameters overlineSCD, the order parameter of the terminal methyl groups SCDCD 3 and the average order parameter for the plateau region overlineSCDPlat of components in the mixtures are compared to those of the pure lipids evaluated in a previous publication Tuchtenhagen et al. Eur. Biophys. J. 23 (1994) 323. The conformational behaviour of lipids in mixtures is mainly influenced by head groups interactions, PAs always being more ordered than the corresponding PCs. Depending on absolute chain length and on chain length differences between the two components different conformational behaviour is observed for the two components in the mixtures, indicating non-ideal mixing and formation of micro-domains in the liquid-crystalline phase. Increases in order at the chain ends with a concomitant decrease in probabilities for end gauche conformations give hints to chain interdigitation in the liquid-crystalline phase.

Ziegler, Wolfgang; Blume, Alfred

1995-09-01

390

The membrane interaction of amphiphilic model peptides affects phosphatidylserine headgroup and acyl chain order and dynamics. Application of the phospholipid headgroup electrometer concept to phosphatidylserine  

SciTech Connect

Deuterium nuclear magnetic resonance ({sup 2}H NMR) was used to study the interaction of amphiphilic model peptides with model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phospho-L-serine deuterated either at the {beta}-position of the serine moiety ((2-{sup 2}H)DOPS) or at the 11-position of the acyl chains ((11,11-{sup 2}H{sub 2})DOPS). The peptides are derived from the sequences H-Ala-Met-Leu-Trp-Ala-OH and H-Arg-Met-Leu-Trp-Ala-OH and contain a positive charge of +1 or +2 at the amino terminus or one positive charge at each end of the molecule. Upon titration of dispersions of DOPS with the peptides, the divalent peptides show a similar extent of binding to the DOPS bilyers, which is larger than that of the single charged peptide. Under these conditions the values of the quadrupolar splitting of both (2-{sup 2}H)DOPS and (11,11-{sup 2}H{sub 2})DOPS are decreased, indicating that the peptides reduce the order of both the DOPS headgroup and the acyl chains. The extent of the decrease depends on the amount of peptide bound and on the position of the charged moieties in the peptide molecule. Titrations of DOPS with poly(L-lysine){sub 100}, which were included for reasons of comparison, reveal increased {Delta}v{sub q} values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component {sup 2}H NMR spectra occur. The apparently limited accessibility of the lipid to the peptides under these circumstances is discussed in relation to the ability of the peptides to exhibit transbilayer movement. {sup 2}H spin-lattice relaxation time T1 measurements demonstrate a decrease of the rates of motion of both headgroup and acyl chains of DOPS in the presence of the peptides.

de Kroon, A.I.P.M.; Killian, J.A.; de Gier, J.; de Kruijff, B. (Univ. of Utrecht (Netherlands))

1991-01-29

391

Large remnant polarization and magnetic field induced destruction of cycloidal spin structure in Bi{sub 1-x}La{sub x}FeO{sub 3} (0 {<=} x {<=} 0.2)  

SciTech Connect

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.

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

392

Chronic exposure to an extremely low-frequency magnetic field induces depression-like behavior and corticosterone secretion without enhancement of the hypothalamic-pituitary-adrenal axis in mice.  

PubMed

An extremely low-frequency magnetic field (ELF-MF) is generated by power lines and household electrical devices. Many studies have suggested an association between chronic ELF-MF exposure and anxiety and/or depression. The mechanism of these effects is assumed to be a stress response induced by ELF-MF exposure. However, this mechanism remains controversial. In the present study, we investigated whether chronic ELF-MF exposure (intensity, 1.5?mT; [corrected] total exposure, 200?h) affected emotional behavior and corticosterone synthesis in mice. ELF-MF-treated mice showed a significant increase in total immobility time in a forced swim test and showed latency to enter the light box in a light-dark transition test, compared with sham-treated (control) mice. Corticosterone secretion was significantly high in the ELF-MF-exposed mice; however, no changes were observed in the amount of the adrenocorticotropic hormone and the expression of genes related to stress response. Quantification of the mRNA levels of adrenal corticosteroid synthesis enzymes revealed a significant reduction in Cyp17a1 mRNA in the ELF-MF-exposed mice. Our findings suggest the possibility that high intensity and chronic exposure to ELF-MF induces an increase in corticosterone secretion, along with depression- and/or anxiety-like behavior, without enhancement of the hypothalamic-pituitary-adrenal axis. PMID:22753092

Kitaoka, Kazuyoshi; Kitamura, Mitsuo; Aoi, Shun; Shimizu, Noriyuki; Yoshizaki, Kazuo

2013-01-01

393

Magnetic order in crocidolite asbestos  

NASA Astrophysics Data System (ADS)

Magnetic properties of two samples of crocidolite (blue asbestos) have been examined using susceptibility and magnetization measurements, neutron diffraction, and Mössbauer spectroscopy. Both samples order magnetically at 30±1 K with a structure in which iron ions in the ribbons parallel to c are all coupled ferromagnetically but the moments of adjacent ribbons are oppositely aligned. The iron moments are oriented at angles of about 69°, 36°, 69° with the a, b, c axes, respectively. A spin flop transition of the antiferromagnetically coupled ribbons occurs in an applied field of 15 kOe at 4.2 K, and a ratio of intraribbon to interribbon exchange interactions of about 10 is inferred. Mössbauer spectra at 4.2 K are decomposed into a ferric pattern with a hyperfine field of 550 kOe, associated with M2 sites, and two ferrous patterns with hyperfine fields of 200 and 100 kOe, associated with M1 and M3 sites, respectively. Each ferrous hyperfine field is oriented perpendicular to V zz , the principal component of the electric field gradient, which is negative for both sites: V zz =-2.65 mm/s, ?=0.1 for M1 and V zz =-2.9 mm/s, ?=0.3 for M3. As in sheet silicates, the field gradients suggest pseudo-trigonal distortions of the ferrous sites symmetry, which stabilize 5 A 1g orbital singlet states.

Moukarika, A.; Coey, J. M. D.; Dang, N. V.

1983-08-01

394

Higher order turbulence closure models  

NASA Technical Reports Server (NTRS)

Theoretical models are developed and numerical studies conducted on various types of flows including both elliptic and parabolic. The purpose of this study is to find better higher order closure models for the computations of complex flows. This report summarizes three new achievements: (1) completion of the Reynolds-stress closure by developing a new pressure-strain correlation; (2) development of a parabolic code to compute jets and wakes; and, (3) application to a flow through a 180 deg turnaround duct by adopting a boundary fitted coordinate system. In the above mentioned models near-wall models are developed for pressure-strain correlation and third-moment, and incorporated into the transport equations. This addition improved the results considerably and is recommended for future computations. A new parabolic code to solve shear flows without coordinate tranformations is developed and incorporated in this study. This code uses the structure of the finite volume method to solve the governing equations implicitly. The code was validated with the experimental results available in the literature.

Amano, Ryoichi S.; Chai, John C.; Chen, Jau-Der

1988-01-01

395

Multilevel hierarchically ordered artificial biomineral.  

PubMed

Living organisms are known for creating complex organic-inorganic hybrid materials such as bone, teeth, and shells, which possess outstanding functions as compared to their simple mineral forms. This has inspired many attempts to mimic such structures, but has yielded few practical advances. In this study, a multilevel hierarchically ordered artificial biomineral (a composite of hydroxyapatite and gelatine) with favorable nanomechanical properties is reported. A typical optimized HAp/gelatin hybrid material in the perpendicular direction of the HAp c-axis has a modulus of 25.91 + 1.78 GPa and hardness of 0.90 + 0.10 GPa, which well matches that of human cortical bone (modulus 24.3 + 1.4 GPa, hardness 0.69 + 0.05 GPa). The bottom-up crystal constructions (from nano- to micro- to macroscale) of this material are achieved through a hard template approach by the phase transformation from DCP to HAp. The structural biomimetic material shows another way to mimic the complex hierarchical designs of sclerous tissues which have potential value for application in hard tissue engineering. PMID:23847156

Liu, Xiaoguo; Lin, Kaili; Wu, Chengtie; Wang, Yueyue; Zou, Zhaoyong; Chang, Jiang

2014-01-15

396

Performances of order statistics CFAR  

NASA Astrophysics Data System (ADS)

A previous analysis of order-statistics constant-false-alarm-rate (OS-CFAR) radar receiving a single pulse from a Rayleigh fluctuating target in a Rayleigh background is extended to a Rayleigh-plus-dominant target. The analysis includes effects of a multitarget environment. A detailed comparison of OS-CFAR, cell-averaging (CA) CFAR, and censored CA-CFAR is provided for a Rayleigh target in the presence of strongly interfering targets. The false-alarm analysis of OS-CFAR is extended to the more general case of a Weibull background. The deterioration of the CFAR property of OS as the shape factor, C, of a Weibull probability density function changes from Rayleigh (C = 2) to a longer-tailed one (C less than 2) is evaluated. The analytic comparison between CA-CFAR and OS-CFAR is extended to an integration of N pulses reflected from a Swerling II target. Here, the OS-CFAR performance (with and without interfering targets) yields an integral equation that is solved numerically.

Shor, Mordechai; Levanon, Nadav

1991-03-01

397

Dislocation sources in ordered intermetallics  

SciTech Connect

An overview on the current understanding of dislocation sources and multiplication mechanisms is made for ordered intermetallic alloys of the L1{sub 2}, B2, and D0{sub 19} structures. In L1{sub 2} alloys, a large disparity of edge/screw segments in their relative mobility reduces the efficiency of a Frank-Read Type multiplication mechanism. In Fe-40%Al of the B2 structure, a variety of dislocation sources are available for <111> slip, including ones resulting from condensation of thermal vacancies. In NiAl with the relatively high APB energy, <100> dislocations may result from the dislocation decomposition reactions, the prismatic punching out from inclusion particles, and/or steps and coated layers of the surface. Internal interfaces often provide sites for dislocation multiplication, e.g., grain boundaries, sub-boundaries in Ni{sub 3}Ga, NiAl and Ti{sub 3}Al, and antiphase domain boundaries in Ti{sub 3}Al. As for the crack tip as a dislocation source, extended SISFs trailed by super-Shockley partials emanating form the cracks in Ni{sub 3}Al and Co{sub 3}Ti are discussed in view of a possible toughening mechanism.

Yoo, M.H. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Appel, F.; Wagner, R. [GKSS-Research Centre, Geesthacht (Germany). Inst. for Materials Research; Mecking, H. [Technical Univ. Hamburg-Harburg, Hamburg (Germany)

1996-09-01

398

Near-field characterization of the optical properties in higher order plasmonic resonances  

NASA Astrophysics Data System (ADS)

Dipole and quadrupole surface plasmon polariton (LSPP) resonances of gold nanoparticle array were directly investigated by a near-field scanning optical microscope (NSOM) in the fiber-collection mode. Separated gold nanoparticles on the quartz substrate were fabricated by nanosphere lithography. Results demonstrate that controlling the incident polarization and angle of oblique incidence enables to excite dipolar and quadrupolar LSPP at 633- and 488-nm excitations. This observation facilitates the understanding of LSPP and interactions with nanostructures in the near field that can be used as a guideline for fabricating nanostructures in controlling spatial distributions of LSPP for ultra sensitive bio-/chemo-detectors or plasmonic metamaterials.

Huang, Chen-Han; Lin, Hsing-Ying; Chang, Chih-Han; Lan, Yun-Chiang; Chui, Hsiang-Chen

2010-01-01

399

The type II superstring to order ? 4  

NASA Astrophysics Data System (ADS)

The Green-Schwarz superstring action in a general type IIA or IIB supergravity background is derived up to fourth order in the Grassmann-odd coordinates ?. This is done by solving the superspace Bianchi identities order by order in ?, to quadratic order for all superfields and to quartic order for the supervielbeins. For a large class of backgrounds it is possible to fix the kappa symmetry in such a way that the action actually terminates at the quartic order in ?.

Wulff, Linus

2013-07-01

400

UNCONDITIONALLY STABLE SCHEMES FOR HIGHER ORDER INPAINTING  

Microsoft Academic Search

Inpainting methods with third and fourth order equations have certain advantages in comparison with equations of second order such as the smooth interpolation of image information even over large distances. Because of this such methods became very popular in the last couple of years. Solving higher order equations numerically can be a computational demanding task though. Discretizing a fourth order

CAROLA-BIBIANE SCH; ANDREA BERTOZZI

401

Higher Order Expectations in Asset Pricing  

Microsoft Academic Search

We examine formally Keynes' idea that higher order beliefs can drive a wedge between an asset price and its fundamental value based on expected future payoffs. Higher order expectations add an additional term to a standard asset pricing equation. We call this the higher order wedge, which depends on the difference between higher and first order expectations of future payoffs.

Philippe Bacchetta; Eric van Wincoop

2008-01-01

402

Genetic Algorithms for Controller Order Reduction  

Microsoft Academic Search

In this paper genetic algorithms are applied as an optimization strategy in a controller order reduction procedure. GAs capability to get out local minima is used to determine a reduced-order controller which optimally approximate the full-order one. Particular attention has been devoted to guarantee a good stability margin and a suitable index is minimized, by using GAs, in order to

Riccardo Caponetto; Luigi Fortuna; Giovanni Muscato; Maria Gabriella Xibilia

1994-01-01

403

46 CFR Sec. 7 - Job order numbering.  

Code of Federal Regulations, 2013 CFR

...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...

2013-10-01

404

A fractional order PID tuning algorithm for a class of fractional order plants  

Microsoft Academic Search

Fractional order dynamic model could model various real materials more adequately than integer order ones and provide a more adequate description of many actual dynamical processes. Fractional order controller is naturally suitable for these fractional order models. In this paper, a fractional order PID controller design method is proposed for a class of fractional order system models. Better performance using

Chunna Zhao; Dingyu Xue; YangQuan Chen

2005-01-01

405

Generalized structure of higher order nonclassicality  

NASA Astrophysics Data System (ADS)

A generalized notion of higher order nonclassicality (in terms of higher order moments) is introduced. Under this generalized framework of higher order nonclassicality, conditions of higher order squeezing and higher order subpoissonian photon statistics are derived. A simpler form of the Hong-Mandel higher order squeezing criterion is derived under this framework by using an operator ordering theorem introduced by us in [A. Pathak, J. Phys. A 33 (2000) 5607]. It is also generalized for multi-photon Bose operators of Brandt and Greenberg. Similarly, condition for higher order subpoissonian photon statistics is derived by normal ordering of higher powers of number operator. Further, with the help of simple density matrices, it is shown that the higher order antibunching (HOA) and higher order subpoissonian photon statistics (HOSPS) are not the manifestation of the same phenomenon and consequently it is incorrect to use the condition of HOA as a test of HOSPS. It is also shown that the HOA and HOSPS may exist even in absence of the corresponding lower order phenomenon. Binomial state, nonlinear first order excited squeezed state (NLESS) and nonlinear vacuum squeezed state (NLVSS) are used as examples of quantum state and it is shown that these states may show higher order nonclassical characteristics. It is observed that the Binomial state which is always antibunched, is not always higher order squeezed and NLVSS which shows higher order squeezing does not show HOSPS and HOA. The opposite is observed in NLESS and consequently it is established that the HOSPS and HOS are two independent signatures of higher order nonclassicality.

Verma, Amit; Pathak, Anirban

2010-02-01

406

On the order of general linear methods.  

SciTech Connect

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.

Constantinescu, E. M.; Mathematics and Computer Science

2009-09-01

407

Birth order effects: A reply to Breland  

Microsoft Academic Search

Answers H. M. Breland's assertions concerning birth order effects in verbal achievement. It is argued that if birth order differences in intellectual functioning exist in childhood, they are very slight and exert at most minimal effects on adult functioning.

Carmi Schooler

1973-01-01

408

The Order of Monotone Piecewise Cubic Interpolation.  

National Technical Information Service (NTIS)

Fritsch and Carlson developed an algorithm which produces a monotone C1 piecewise cubic interpolant to a monotone function. We show that the algorithm yields a third-order approximation, while a modification is fourth-order accurate. (Author)

S. C. Eisenstat K. R. Jackson J. W. Lewis

1981-01-01

409

Logistic Order Statistics and Their Properties.  

National Technical Information Service (NTIS)

Order statistics from the logistic distribution have been studied and their moments and distributional properties have been discussed. Recurrence relations satisfied by the single and the product moments of order statistics are presented. Series expansion...

N. Balakrishnan S. S. Gupta

1990-01-01

410

48 CFR 52.216-18 - Ordering.  

Code of Federal Regulations, 2013 CFR

...issuedâ 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,...

2013-10-01

411

Telecommunications Approach to Updating Technical Orders.  

National Technical Information Service (NTIS)

The Joint Service Technical Information System (JUSTIS--formerly the Air Force Technical Order Management System) was chartered to improve the way in which the Air Force and other services manage technical orders (TOs). Because of the involvement that TOs...

C. W. Fox

1990-01-01

412

Specific RNA binding to ordered phospholipid bilayers  

Microsoft Academic Search

We have studied RNA binding to vesicles bounded by ordered and disordered phospholipid membranes. A positive correlation exists between bilayer order and RNA affinity. In particular, structure-dependent RNA binding appears for rafted (liquid-ordered) domains in sphingomyelin-cholesterol-1,2-dioleoyl-sn-glycero- 3-phosphocholine vesicles. Binding to more highly ordered gel phase membranes is stronger, but much less RNA structure-dependent. All modes of RNA-membrane association seem to

Tadeusz Janas; Teresa Janas; Michael Yarus

2006-01-01

413

Contact Geometry of Second Order I  

Microsoft Academic Search

Classical theory for systems of the first order partial differential equations for a scalar function can be rephrased as the\\u000a submanifold theory of contact manifolds (geometric first order jet spaces). In the same spirit, we will develop the geometric\\u000a theory of systems of partial differential equations of second order for a scalar function as the Contact Geometry of Second Order,

Keizo Yamaguchi

414

Second-order mathematical theory of computation  

Microsoft Academic Search

In this work we show that it is possible to formalize all properties regularly observed in (deterministic and non-deterministic) algorithms in second-order predicate calculus. Moreover, we show that for any given algorithm it suffices to know how to formalize its 'partial correctness' by a second-order formula in order to formalize all other properties by second-order formulas. This result is of

Zohar Manna

1970-01-01

415

Vector spaces with an order unit  

Microsoft Academic Search

We develop a theory of ordered *-vector spaces with an order unit. We prove\\u000afundamental results concerning positive linear functionals and states, and we\\u000ashow that the order (semi)norm on the space of self-adjoint elements admits\\u000amultiple extensions to an order (semi)norm on the entire space. We single out\\u000athree of these (semi)norms for further study and discuss their significance

Vern I. Paulsen; Mark Tomforde

2009-01-01

416

Topological properties of spaces ordered by preferences  

Microsoft Academic Search

In this paper, we analyze the main topological properties of a relevant class of topologies associated with spaces ordered by preferences (asymmetric, negatively transi- tive binary relations). This class consists of certain continuous topologies which include the order topology. The concept of saturated identification is introduced in order to provide a natural proof of the fact that all these spaces

J. C. R. Alcantud

1999-01-01

417

An overview of task order 10  

Microsoft Academic Search

Task Order 10 formalizes a collaboration in high explosive pulsed power (HEPP) experiments between LANL and VNIIEF. The focus is the VNIIEF disk explosive magnetic generator (DEMG) technology. The task order outlines a sequence of tasks and deliverables culminating in an experiment which takes place in the US utilizing US explosives and a Russian DEMG. This talk summarizes task order

Rousculp; Christopher L

2011-01-01

418

High order methods for electromagnetics simulation  

Microsoft Academic Search

Higher order methods in electromagnetics are of interest to the PIC community in modeling electromagnetic wave propagation in cavities. It is believed that high order numerical methods have advantages over lower order methods as they can produce equivalently accurate solutions at lower resolution and thus potentially at lower computational cost. In this paper we present the algorithm and result of

John Loverich; Ammar Hakim

2007-01-01

419

Birth order as a market segmentation variable  

Microsoft Academic Search

Birth order studies have an established history in the academic world just as demographics have an established history in marketing. Discusses how birth order may influence several socio-economic mechanisms and thereby influence select consumption behaviors. As a likely influence of certain consumption behaviors, birth order may be useful in segmenting certain markets. Offers a corporate advertising example to demonstrate the

Reid P. Claxton

1995-01-01

420

A Study of Orders in Quaternion Algebras.  

National Technical Information Service (NTIS)

For each A-order Lambda in a generalized quaternion algebra H over the field of fractions F of a Dedekind ring A, its Gorenstein closure is defined. This is a Gorenstein A-order G (Lambda) in H such that Lambda is the least A-order containing (b underline...

J. Brzezinski

1981-01-01

421

Abel's Theorem Simplifies Reduction of Order  

ERIC Educational Resources Information Center

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.

Green, William R.

2011-01-01

422

Diachronic Reanalysis in French: Resistant Word Orders.  

ERIC Educational Resources Information Center

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

Guillory, Helen Gant

1994-01-01

423

20 CFR 655.121 - Job orders.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Job orders. 655.121 Section 655.121... Prefiling Procedures § 655.121 Job orders. (a) Area of intended employment...Certification, the employer must submit a job order, Form ETA-790, to the SWA...

2013-04-01

424

Application Specific Higher Order Logic Theorem Proving  

Microsoft Academic Search

Theorem proving allows the formal verification of the correctness of very large systems. In order to increase the acceptance of theorem proving systems during the design process, we implemented higher order logic proof systems for ANSI-C and Verilog within a framework for application specific proof systems. Furthermore, we implement the language of the PVS theorem prover as well-established higher order

Daniel Kroening

2002-01-01

425

Order Estimation of Multivariate ARMA Models  

Microsoft Academic Search

Model order estimation is fundamental in the system identification process. In this paper, we generalize a previous multivariate autoregressive (AR) model order estimation method (J. Lardies and N. Larbi, ??A new method for model order selection and model parameter estimation in time domain,?? J. Sound Vibr., vol. 245, no. 2, 2001) to include multivariate autoregressive moving average (ARMA) models and

Tracey Cassar; Kenneth P. Camilleri; Simon G. Fabri

2010-01-01

426

Orders of Growth of Real Functions  

Microsoft Academic Search

In this paper we define the notion of order of a function, which measures its growth rate with respect to a given function. We introduce the notions of continuity and linearity at infinity with which we characterize order-comparability and equivalence. Using the theory we have developed, we apply orders of functions to give a simple and natural criterion for the

Titus Hilberdink

2007-01-01

427

Eric Voegelin's order in history: A review  

Microsoft Academic Search

ORDER IN HISTORY, Vol. I, ISREAL AND REVELATION. By Eric Voegelin. Baton Rouge: Louisiana State University Press, 1956; pp. xxvi + 534. $19.95.ORDER IN HISTORY, Vol. II, THE WORLD OF THE POLIS. By Eric Voegelin. Baton Rouge: Louisiana State University Press, 1957; pp. xvii + 390. $19.95.ORDER IN HISTORY, Vol. III, PLATO AND ARISTOTLE. By Eric Voegelin. Baton Rouge: Louisiana

John Angus Campbell

1982-01-01

428

Methodology, Birth Order, Intelligence, and Personality.  

ERIC Educational Resources Information Center

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…

Michalski, Richard L.; Shackelford, Todd K.

2001-01-01

429

Competing orders in the cuprate superconductors  

NASA Astrophysics Data System (ADS)

When the superconducting order in a doped cuprate system is suppressed, for example by magnetic field, impurities, finite temperature or less optimal doping condition, various competing orders are revealed. This thesis contains the theoretical analysis of these competing orders, especially the analysis of the quantum phase transitions from a d-wave superconductor to a superconductor featuring a certain other order. Such orders can be divided into two types according to whether or not they carry non-zero net momentum Q. We classify and analyze all order parameters with Q = 0 on the basis of group-theoretic and symmetry arguments. Thereafter, by a renormalization group analysis, we identify that among all these orders the fluctuations of dx2 - y2 + idxy paring order might strongly damp the nodal quasiparticles of the cuprate superconductor, while leaving antinodal quasiparticles undamped. We also study order parameters with Q ? 0, which include spin and charge density wave orders. For exact nesting case, fluctuations of these two orders also give rise to nodal quasiparticle damping. We also examine the influence of a magnetic field on the spin and charge density waves. We argue that the underdoped cuprates might undergo a second order phase transition into a region where superconducting order coexists with long-range magnetic order (and hence charge order). The transition might be driven by lowering the doping or increasing the magnetic field, all of which decrease the spin gap and affect the excitation spectrum. Our quantum field theory for the transition takes into account the quantum fluctuation of spin order, while keeping superconducting order a mean-field quantity that serves as a tuning parameter by coupling to spin order. Complete numerical solutions of a self-consistent large-N theory provide detailed information on the phase diagram and the spatial structure of the dynamic spin spectrum. We also compute the pinning of charge density order by the vortices where the spin order dynamically fluctuates. Emerging experimental evidence has strongly supported our theory and the subsequent predictions.

Zhang, Ying

430

Higher-order artificial neural networks  

SciTech Connect

The report investigates the storage capacity of an artificial neural network where the state of each neuron depends on quadratic correlations of all other neurons, i.e. a third order network. This is in contrast to a standard Hopfield network where the state of each single neuron depends on the state on every other neuron, without any correlations. The storage capacity of a third order network is larger than that for standard Hopfield by one order of N. However, the number of connections is also larger by an order of N. It is shown that the storage capacity per connection is identical for standard Hopfield and for this third order network.

Bengtsson, M.

1990-12-01

431

High order methods for electromagnetics simulation  

NASA Astrophysics Data System (ADS)

Higher order methods in electromagnetics are of interest to the PIC community in modeling electromagnetic wave propagation in cavities. It is believed that high order numerical methods have advantages over lower order methods as they can produce equivalently accurate solutions at lower resolution and thus potentially at lower computational cost. In this paper we present the algorithm and result of electromagnetic simulations of the crab cavity using a higher than second order numerical wave propagation algorithm. Ultimately this high order scheme will be implemented in the plasma code VORPAL where it will be tested on a variety of computational plasma problems.

Loverich, John; Hakim, Ammar

2007-11-01

432

Higher order Godunov schemes for isothermal hydrodynamics  

NASA Technical Reports Server (NTRS)

In this paper we construct higher order Godunov schemes for isothermal flow. Isothermal hydrodynamics serves as a good representation for several systems of astrophysical interest. The schemes designed here have second-order accuracy in space and time and some are third-order accurate for advection. Moreover, several ingredients of these schemes are essential components of even higher order. The methods designed here have excellent ability to represent smooth flow yet capture shocks with high resolution. Several test problems are presented. The algorithms presented here are compared with other algorithms having a comparable formal order of accuracy.

Balsara, Dinshaw S.

1994-01-01

433

First-order inflation. [in cosmology  

NASA Technical Reports Server (NTRS)

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.

Kolb, Edward W.

1991-01-01

434

Ionic Conductivity of Block Copolymer Electrolytes in the Vicinity of Order?Disorder and Order?Order Transitions  

SciTech Connect

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.

Wanakule, Nisita S.; Panday, Ashoutosh; Mullin, Scott A.; Gann, Eliot; Hexemer, Alex; Balsara, Nitash P.; (UCB); (LBNL)

2009-09-15

435

Control of Initialized Fractional-Order Systems  

NASA Technical Reports Server (NTRS)

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.

Hartly, Tom T.; Lorenzo, Carl F.

2002-01-01

436

Two variants of minimum discarded fill ordering  

SciTech Connect

It is well known that the ordering of the unknowns can have a significant effect on the convergence of Preconditioned Conjugate Gradient (PCG) methods. There has been considerable experimental work on the effects of ordering for regular finite difference problems. In many cases, good results have been obtained with preconditioners based on diagonal, spiral or natural row orderings. However, for finite element problems having unstructured grids or grids generated by a local refinement approach, it is difficult to define many of the orderings for more regular problems. A recently proposed Minimum Discarded Fill (MDF) ordering technique is effective in finding high quality Incomplete LU (ILU) preconditioners, especially for problems arising from unstructured finite element grids. Testing indicates this algorithm can identify a rather complicated physical structure in an anisotropic problem and orders the unknowns in the preferred'' direction. The MDF technique may be viewed as the numerical analogue of the minimum deficiency algorithm in sparse matrix technology. At any stage of the partial elimination, the MDF technique chooses the next pivot node so as to minimize the amount of discarded fill. In this work, two efficient variants of the MDF technique are explored to produce cost-effective high-order ILU preconditioners. The Threshold MDF orderings combine MDF ideas with drop tolerance techniques to identify the sparsity pattern in the ILU preconditioners. These techniques identify an ordering that encourages fast decay of the entries in the ILU factorization. The Minimum Update Matrix (MUM) ordering technique is a simplification of the MDF ordering and is closely related to the minimum degree algorithm. The MUM ordering is especially for large problems arising from Navier-Stokes problems. Some interesting pictures of the orderings are presented using a visualization tool. 22 refs., 4 figs., 7 tabs.

D'Azevedo, E.F. (Oak Ridge National Lab., TN (USA)); Forsyth, P.A.; Tang, Wei-Pai (Waterloo Univ., ON (Canada). Dept. of Computer Science)

1991-01-01

437

Synchronization of chaotic systems with different order.  

PubMed

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

Femat, Ricardo; Solís-Perales, Gualberto

2002-03-01

438

Investigation on improved Gabor order tracking technique  

NASA Astrophysics Data System (ADS)

The study proposes an improved Gabor order tracking (GOT) technique to cope with crossing orders that cannot be effectively separated using the original GOT scheme. The improvement aids both the reconstruction and interpretation of two crossing orders such as a transmission-element-regarding order component and a structural resonant component. In the paper, the influence of the dual function to Gabor expansion coefficients is investigated, which can affect the precision of the tracked order component. Additionally, using the GOT scheme in noise conditions is demonstrated as well. For applying the improved GOT in real tasks, separation and extraction of close-order components of vibration signals measured from a transmission-element test bench is illustrated using both the GOT and Vold-Kalman filtering (VKF) OT schemes. Finally, comprehensive comparisons between the improved GOT and VKF_OT schemes are made from processing results.

Pan, Min-Chun; Chiu, Chun-Ching

2004-07-01

439

Invariant Higher-Order Variational Problems  

NASA Astrophysics Data System (ADS)

We investigate higher-order geometric k-splines for template matching on Lie groups. This is motivated by the need to apply diffeomorphic template matching to a series of images, e.g., in longitudinal studies of Computational Anatomy. Our approach formulates Euler-Poincaré theory in higher-order tangent spaces on Lie groups. In particular, we develop the Euler-Poincaré formalism for higher-order variational problems that are invariant under Lie group transformations. The theory is then applied to higher-order template matching and the corresponding curves on the Lie group of transformations are shown to satisfy higher-order Euler-Poincaré equations. The example of SO(3) for template matching on the sphere is presented explicitly. Various cotangent bundle momentum maps emerge naturally that help organize the formulas. We also present Hamiltonian and Hamilton-Ostrogradsky Lie-Poisson formulations of the higher-order Euler-Poincaré theory for applications on the Hamiltonian side.

Gay-Balmaz, François; Holm, Darryl D.; Meier, David M.; Ratiu, Tudor S.; Vialard, François-Xavier

2012-01-01

440

Formation of nematic ordered cellulose and chitin  

Microsoft Academic Search

We proposed in a previous paper a unique form of ß-glucan association, nematic ordered cellulose (NOC) that is molecularly ordered, yet non-crystalline. NOC has unique characteristics; in particular, its surface properties provide with a function of tracks or scaffolds for regulated movements and fiber-production of Acetobacter xylinum [Kondo et al. 2002. Proc. Natl. Acad. Sci. USA 99: 14008–14013]. In order

Tetsuo Kondo; Wakako Kasai; R. Malcolm Brown

2004-01-01

441

The Twelve Soil Orders - Soil Taxonomy  

NSDL National Science Digital Library

This University of Idaho website discusses the twelve orders of soils, and provides images that illustrate the distribution, properties, and use of the soil orders. It provides general information on each of the twelve orders with a description, a U.S. map showing soil locations, and pictures of the soil type. A Global Distribution Map indicates locations of each soil type throughout the world.

442

Exact significance test for Markov order  

NASA Astrophysics Data System (ADS)

We describe an exact significance test of the null hypothesis that a Markov chain is nth order. The procedure utilizes surrogate data to yield an exact test statistic distribution valid for any sample size. Surrogate data are generated using a novel algorithm that guarantees, per shot, a uniform sampling from the set of sequences that exactly match the nth order properties of the observed data. Using the test, the Markov order of Tel Aviv rainfall data is examined.

Pethel, S. D.; Hahs, D. W.

2014-02-01

443

Quasi-Fibonacci Numbers of Order 11  

NASA Astrophysics Data System (ADS)

In this paper we introduce and investigate the so-called quasi-Fibonacci numbers of order 11 . These numbers are defined by five conjugate recurrence equations of order five. We study some relations and identities concerning these numbers. We present some applications to the decomposition of some polynomials. Many of the identities presented here are the generalizations of the identities characteristic for general recurrence sequences of order three given by Rabinowitz.

Witu?a, Roman; S?ota, Damian

2007-08-01

444

Epsilon Negative Zeroth-Order Resonator Antenna  

Microsoft Academic Search

It is confirmed that zeroth-order resonance appears in the epsilon negative (ENG) meta-structured transmission line (MTL) as well as in the conventional double negative (DNG) MTL. The zeroth-order resonant characteristics are described using dispersion relation of ENG MTL based on Bloch and Floquet theory. Appling the novel concept of the ENG zeroth-order resonator (ZOR), an ENG ZOR antenna is proposed.

Jae-Hyun Park; Young-Ho Ryu; Jae-Gon Lee; Jeong-Hae Lee

2007-01-01

445

Second-order dust acoustic wave theory  

NASA Astrophysics Data System (ADS)

A second-order perturbation theory for non-dispersive, undamped dust acoustic waves is presented. The analysis leads to a second-order wave equation with source terms consisting of (nonlinear) products of first-order terms. The nonlinear effects included in this analysis might be useful in explaining the non-sinusoidal waveforms that are observed with large-amplitude, self-excited dust acoustic waves.

Merlino, Robert L.

2012-03-01

446

Partial Order Semantics and Read Arcs  

Microsoft Academic Search

We study a new partial order semantics of Petri nets with read arcs, whereread arcs model reading without consuming, which is often more adequate thanthe destructive-read-and-rewrite modelled in ordinary nets. As basic observationswe take ST-traces, which are sequences of transition starts and ends. We defineprocesses of our nets and derive two partial orders modelling causality and startprecedence. These partial orders

Walter Vogler

1997-01-01

447

Plaquette ordering in SU(4) antiferromagnets  

NASA Astrophysics Data System (ADS)

We use fermion mean-field theory to study possible plaquette ordering in the antiferromagnetic SU(4) Heisenberg model. We find the ground state for both the square and triangular lattices to be the disconnected plaquette state. Our mean-field theory gives a first-order transition for plaquette ordering for the triangular lattice. Our results suggest a large number of low-lying states.

Mishra, Anup; Ma, Michael; Zhang, Fu-Chun

2002-06-01

448

Reduced-Order Models for MEMS Applications  

Microsoft Academic Search

We review the development of reduced-order models for MEMS devices. Based on their implementation procedures, we classify these reduced-order models into two broad categories: node and domain methods. Node methods use lower-order approximations of the system matrices found by evaluating the system equations at each node in the discretization mesh. Domain-based methods rely on modal analysis and the Galerkin method

ALI H. NAYFEH; MOHAMMAD I. YOUNIS; EIHAB M. ABDEL-RAHMAN

2005-01-01

449

Generalized Predictive Control of Arbitrary Real Order  

Microsoft Academic Search

\\u000a This paper proposes Fractional–Order Generalized Predictive Control (FGPC), a model-predictive control methodology that makes\\u000a use of a cost function of arbitrary real order. FGPC uses two scalar parameters that represent fractional-order differentiation.\\u000a These parameters can be tuned to achieve closed-loop specifications in a way much easier and faster than using the classical\\u000a GPC weighting sequences.

Miguel Romero Hortelano; Ángel Pérez Madrid y Pablo; Carolina Mañoso Hierro; Roberto Hern ´ andez Berlinches

450

The Market Impact of a Limit Order  

Microsoft Academic Search

Despite their importance in modern electronic trading, virtually no systematic empirical evidence on the market impact of incoming orders is existing. We quantify the short-run and long-run price effect of posting a limit order by proposing a high-frequency cointegrated VAR model for ask and bid quotes and several levels of order book depth. Price impacts are estimated by means of

Nikolaus Hautsch; Ruihong Huang

2009-01-01

451

Understanding fractional-order surface plasmons.  

PubMed

We show experimentally that diffraction-induced surface plasmon excitation can mimic enhanced transmission and cause a highly sensitive modulation by the coherent interference between zero-order and reflected first-order diffraction in select regions of the terahertz spectrum. Based on the study of a one-dimensional metallic grating, we obtain the physical mechanisms of the fractional-order surface plasmon resonances observed with the two-dimensional grating of the metallic hole array. PMID:22048370

Yang, Yuping; Grischkowsky, Daniel

2011-11-01

452

Second order hydrodynamic coefficients from kinetic theory  

SciTech Connect

In a relativistic setting, hydrodynamic calculations which include shear viscosity (which is first order in an expansion in gradients of the flow velocity) are unstable and acausal unless they also include terms to second order in gradients. To date such terms have only been computed in supersymmetric N=4 super-Yang-Mills theory at infinite coupling. Here we compute these second-order hydrodynamic coefficients in weakly coupled QCD, perturbatively to leading order in the QCD coupling, using kinetic theory. We also compute them in QED and scalar {lambda}{phi}{sup 4} theory.

York, Mark Abraao; Moore, Guy D. [McGill University, Department of Physics, 3600 rue University, Montreal QC H3A 2T8 (Canada)

2009-03-01

453

Electromagnetic generation of acoustic waves near second-order magnetic phase transitions of the ``order-disorder'' and ``order-order'' type  

NASA Astrophysics Data System (ADS)

In this work, we theoretically and experimentally established the common feature of the evolution of the efficiency of the electromagnetic generation of acoustic waves near the temperatures of second-order magnetic phase transitions characteristic of both the “order-disorder” (Curie point in isotropic ferromagnets) and “order-order” (easy-axis-angular-phase and angular-phase-easy-plane) transitions in uniaxial magnets, which consists in the fact that the peak of efficiency corresponds precisely to these temperatures at any values of the magnetic field even if in a magnetic field these temperatures cease to be the points of phase transitions.

Il'Yasov, R. S.; Glavatskikh, M. Yu.

2010-04-01

454

Order parameter symmetry in ferromagnetic superconductors  

NASA Astrophysics Data System (ADS)

We analyze the symmetry and nodal structure of the superconducting order parameter in a cubic ferromagnet, such as ZrZn2. We demonstrate how the order parameter symmetry evolves when the electromagnetic interaction of the conduction electrons with the internal magnetic induction and the spin-orbit coupling are taken into account. These interactions break the cubic symmetry and lift the degeneracy of the order parameter. It is shown that the order parameter which appears immediately below the critical temperature has two components, and its symmetry is described by corepresentations of the magnetic point groups. This allows us to make predictions about the location of the gap nodes.

Samokhin, K. V.; Walker, M. B.

2002-11-01

455

Pi Bond Orders and Bond Lengths  

ERIC Educational Resources Information Center

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)

Herndon, William C.; Parkanyi, Cyril

1976-01-01

456

An Empirical Analysis of the Limit Order Book and the Order Flow in the Paris Bourse  

Microsoft Academic Search

As a centralized, computerized, limit order market, the Paris Bourse is particularly appropriate for studying the interaction between the order book and order flow. Descriptive methods capture the richness of the data and distinctive aspects of the market structure. Order flow is concentrated near the quote, while the depth of the book is somewhat larger at nearby valuations. We analyze

Bruno Biais; Pierre Hillion; Chester Spatt

1995-01-01

457

Birth Order and Marital Bliss in Israel  

ERIC Educational Resources Information Center

This study offers a rank order of successful marriages, according to birth order in Israel. The results of two studies show that marriage consisting of a first born and a later born are more successful than marriages composed of two first borns or two later borns. (Author/PC)

Weller, Leonard; And Others

1974-01-01

458

Exploring Partial Order of European Countries  

ERIC Educational Resources Information Center

Partial Order Theory has been recently more and more employed in applied science to overcome the intrinsic disadvantage hidden in aggregation, if a multiple attribute system is available. Despite its numerous positive features, there are many practical cases where the interpretation of the partial order can be rather troublesome. In these cases…

Annoni, Paola; Bruggemann, Rainer

2009-01-01

459

Discrete nonlinear estimators of fixed order  

Microsoft Academic Search

We present a method of discrete time nonlinear filtering with a filter of reduced order, and with the filter designed to have a property of bias removal. The technique is based on keeping up to second order terms in the Taylor series of the nonlinearities about the estimate. At the stage of filter design, we limit the complexity of the

Hoowang Shim; C. S. Sims; Eamonn McQuade

1997-01-01

460

Few Fractional Order Derivatives and Their Computations  

ERIC Educational Resources Information Center

This work presents an introductory development of fractional order derivatives and their computations. Historical development of fractional calculus is discussed. This paper presents how to obtain computational results of fractional order derivatives for some elementary functions. Computational results are illustrated in tabular and graphical…

Bhatta, D. D.

2007-01-01

461

Rook numbers and the normal ordering problem  

Microsoft Academic Search

For an element w in the Weyl algebra generated by D and U with relation DU = UD + 1, the normally ordered form is w = P ci,jU iDj. We demonstrate that the normal order coefficientsci,j of a word w are rook num- bers on a Ferrers board. We use this interpretation to give a new proof of the

Anna Varvak

2005-01-01

462

Third order harmonics generation in multilayer nanoshells  

NASA Astrophysics Data System (ADS)

Third order harmonics generation has been investigated for multilayer nanoshell structure. Numerical calculations show that the nonlinear susceptibility of this structure depends on the parameters such as size and kind of structure, relaxation time and pump photon energy. The intensity and position of third order nonlinear susceptibility peaks depend on shell thicknesses; smaller thicknesses have peak susceptibility at shorter wavelength.

Bahari, Ali; Moghadam, Fereshteh Rahimi

2012-07-01

463

Pedophilia, Sexual Orientation, and Birth Order  

Microsoft Academic Search

This study extended research on birth order and erotic preferences by examining birth order in a sample of pedophiles. Charts of 338 pedophiles, assessed from 1980–1994 in the Behavioural Sexology Department of the Clarke Institute of Psychiatry in Toronto, were reviewed for family–demographic information. In total, 170 (57 heterosexual pedophiles, 68 homosexual pedophiles, and 45 bisexual pedophiles) of these men

Anthony F. Bogaert; Scott Bezeau; Michael Kuban; Ray Blanchard

1997-01-01

464