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Sample records for earth quadrupolar effects

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

    NASA Technical Reports Server (NTRS)

    Cox, D. L.

    1987-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Cox, D. L.

    1987-01-01

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

  3. Effects of the quadrupolar interaction in Γ3-Γ4 systems observed through a reduced model

    NASA Astrophysics Data System (ADS)

    von Ranke, P. J.; Caldas, A.; de Oliveira, N. A.; Palermo, L.

    1997-07-01

    We study the magnetism of PrX2 intermetallic compounds (X = Rh, Al, Ru Mg) on the basis of a Hamiltonian which includes the quadrupolar interaction in addition to the magnetic and crystal field interactions. The calculations are carried out through a reduced model in which we neglect the highest energy levels of the ground state multiplet of the Pr ion. In this simplified picture, we obtain an analytic expression for the magnetic state equation. This equation is used to investigate how the quadrupolar interaction affects the nature of the magnetic phase transition. We also investigate the effects of the quadrupolar interaction on the behaviour of the gyromagnetic and dipolar exchange parameters in the present PrX2 compounds.

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

    PubMed Central

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

    2016-01-01

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

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

    SciTech Connect

    Urban, Jeffry Todd

    2004-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  7. Quadrupolar Effect on Two Layered Thin Film Antiferroelectric Smectic Liquid Crystal

    SciTech Connect

    Lum, Chia-Yuee; Ong, Lye-Hock; Cepic, Mojca

    2011-03-30

    Within the framework of the discrete Landau phenomenological model, the free energy of an antiferroelectric smectic liquid crystal is analyzed. This model considers the interactions between the liquid crystal molecules within the nearest and the next nearest layers. Electrostatic quadrupolar interaction up to the nearest layers is included. This quadrupolar term, b{sub q{xi}}???{sub i{center_dot}{xi}}???{sub i+1}{sup 2} is positive, thus favouring a perpendicular orientation in the adjacent layer respectively. We show how quadrupolar interaction can affects the planar regions of the phase diagram of a two layered thin antiferroelectric smectic liquid crystal film.

  8. The Effect of Tidal Friction and Quadrupolar Distortion on Orbits of Stars or Planets in Hierarchical Triple systems

    NASA Astrophysics Data System (ADS)

    Kiseleva, L. G.; Eggleton, P. P.

    In hierarchical triple stars, such as lambda Tau and beta Per the combination of a) fluctuating eccentricity due to the third body and b) tidal friction, mainly within the close pair, which tries to remove such fluctuations, can lead to potentially large but slow secular changes in orbital parameters. We model the orbits of both the above systems using a force law which includes a combination of point-mass gravity, quadrupolar distortion of each star by the other two, and a dissipative tidal-friction term. For lambda Tau we find a preferred model where expansion of the inner orbit due to mass transfer on a nuclear timescale is balanced by contraction because tidal friction transfers angular momentum from the inner to the outer orbit. In beta Per, the two orbits are nearly orthogonal (i=100 deg), and the effect of the third star would periodically increase the inner eccentricity up to nearly unity if we neglect the effects of quadrupolar distortion and tidal friction. In fact, in beta Per quadrupolar distortion alone can almost completely suppress the inner eccenticity fluctuations. In a hypothetcal zero-age state of this system, when the inner binary can be supposed to be well-detached, we find large fluctuations in eccentricity which, on being damped by tidal friction, lead to shrinkage of the inner orbit on a surprisingly short timescale. However, the shrinkage is halted by the fact that as the inner pair becomes closer they become more distorted: this quadrupolar distortion leads to apsidal motion which prevents further large fluctuations in eccentricity. In hypothetical cases of nearly orthogonal triple systems with one component of the close pair being a Jupiter-like planet, the combined effect of quadrupolar distortion and tidal friction may reduce the fluctuations of the inner eccentricity, and in some cases the Jupiter orbit can in principle be shrunk quite drastically over a suitably long interval of time. This is potentially important for the long

  9. Boundary conditions for quadrupolar metamaterials

    NASA Astrophysics Data System (ADS)

    Silveirinha, Mário G.

    2014-08-01

    One of the long-standing problems in effective medium theories is using the knowledge of the bulk material response to predict the behavior of the electromagnetic fields at the material boundaries. Here, using a first principles approach, we derive the boundary conditions satisfied by the macroscopic fields at interfaces between reciprocal metamaterials with a quadrupolar-type response. Our analysis reveals that in addition to the usual Maxwellian-type boundary conditions for the tangential fields, in general—to ensure the conservation of the power flow and Lorentz reciprocity—it is necessary to enforce an additional boundary condition (ABC) at an interface between a quadrupolar material and a standard dielectric. It is shown that the ABC is related to the emergence of an additional wave in the bulk quadrupolar medium.

  10. Magnetic Structure and Quadrupolar Order Parameter Driven by Geometrical Frustration Effect in NdB4

    NASA Astrophysics Data System (ADS)

    Yamauchi, Hiroki; Metoki, Naoto; Watanuki, Ryuta; Suzuki, Kazuya; Fukazawa, Hiroshi; Chi, Songxue; Fernandez-Baca, Jaime A.

    2017-04-01

    Neutron diffraction experiments have been carried out to characterize the magnetic structures and order parameters in an intermediate phase of NdB4 showing the successive phase transitions at T0 = 17.2 K, TN1 = 7.0 K, and TN2 = 4.8 K. We have revealed the antiferromagnetic ordering with the propagation vectors q0 = (0,0,0), q0 and qs1 = (δ ,δ ,0.4) (δ ˜ 0.14), and q0 and qs2 = (0.2,0,0.4) in phase II (TN1 < T < T0), phase III (TN2 < T < TN1), and phase IV (T < TN2), respectively. The observed patterns in phase II are successfully explained by postulating a coplanar structure with static magnetic moments in the tetragonal ab-plane. We have found that the magnetic structure in phase II can be uniquely determined to be a linear combination of antiferromagnetic "all-in/all-out"-type (Γ4) and "vortex"-type (Γ2) structures, consisting of a Γ4 main component (77%) with a small amplitude of Γ2 (23%). We propose that the quadrupolar interaction holds the key to stabilizing the noncollinear magnetic structure and quadrupolar order. Here, the frustration in the Shastry-Sutherland lattice would play an essential role in suppressing the dominance of the magnetic interaction.

  11. The Effect of Combined Magnetic Geometries on Thermally Driven Winds. I. Interaction of Dipolar and Quadrupolar Fields

    NASA Astrophysics Data System (ADS)

    Finley, Adam J.; Matt, Sean P.

    2017-08-01

    Cool stars with outer convective envelopes are observed to have magnetic fields with a variety of geometries, which on large scales are dominated by a combination of the lowest-order fields such as the dipole, quadrupole, and octupole modes. Magnetized stellar wind outflows are primarily responsible for the loss of angular momentum from these objects during the main sequence. Previous works have shown the reduced effectiveness of the stellar wind braking mechanism with increasingly complex but singular magnetic field geometries. In this paper, we quantify the impact of mixed dipolar and quadrupolar fields on the spin-down torque using 50 MHD simulations with mixed fields, along with 10 each of the pure geometries. The simulated winds include a wide range of magnetic field strength and reside in the slow-rotator regime. We find that the stellar wind braking torque from our combined geometry cases is well described by a broken power-law behavior, where the torque scaling with field strength can be predicted by the dipole component alone or the quadrupolar scaling utilizing the total field strength. The simulation results can be scaled and apply to all main-sequence cool stars. For solar parameters, the lowest-order component of the field (dipole in this paper) is the most significant in determining the angular momentum loss.

  12. The combined effect of quadrupolar and dipolar interactions on the excitation and evolution of triple quantum coherences in ⁷Li solid state magic angle spinning NMR.

    PubMed

    Eliav, Uzi; Goldbourt, Amir

    2013-05-01

    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 π/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. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Effective Floquet Hamiltonians for dipolar and quadrupolar coupled N-spin systems in solid state nuclear magnetic resonance under magic angle spinning.

    PubMed

    Pandey, Manoj Kumar; Krishnan, Mangala Sunder

    2010-11-07

    Spin dynamics under magic angle spinning has been studied using different theoretical approaches and also by extensive numerical simulation programs. In this article we present a general theoretical approach that leads to analytic forms for effective Hamiltonians for an N-spin dipolar and quadrupolar coupled system under magic angle spinning (MAS) conditions, using a combination of Floquet theory and van Vleck (contact) transformation. The analytic forms presented are shown to be useful for the study of MAS spin dynamics in solids with the help of a number of simulations in two, three, and four coupled, spin-1/2 systems as well as spins in which quadrupolar interactions are also present.

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

    PubMed

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

    2013-02-01

    Scalar coupling relaxation, which is usually only associated with closely resonant nuclei (e.g., (79)Br-(13)C), can be a very effective relaxation mechanism. While working on hyperpolarized [5-(13)C]glutamine, fast liquid-state polarization decay during transfer to the MRI scanner was observed. This behavior could hypothetically be explained by substantial T(1) shortening due to a scalar coupling contribution (type II) to the relaxation caused by the fast-relaxing quadrupolar (14)N adjacent to the (13)C nucleus in the amide group. This contribution is only effective in low magnetic fields (i.e., less than 800 μT) and prevents the use of molecules bearing the (13)C-amide group as hyperpolarized MRS/MRI probes. In the present work, this hypothesis is explored both theoretically and experimentally. The results show that high hyperpolarization levels can be retained using either a (15)N-labeled amide or by applying a magnetic field during transfer of the sample from the polarizer to the MRI scanner. Copyright © 2012 Elsevier Inc. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Smith, Scott A.; Murali, Nagarajan

    1999-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  19. Phase transitions of quadrupolar fluids

    NASA Astrophysics Data System (ADS)

    O'Shea, Seamus F.; Dubey, Girija S.; Rasaiah, Jayendran C.

    1997-07-01

    Gibbs ensemble simulations are reported for Lennard-Jones particles with embedded quadrupoles of strength Q*=Q/(ɛσ5)1/2=2.0 where ɛ and σ are the Lennard-Jones parameters. Calculations revealing the effect of the dispersive forces on the liquid-vapor coexistence were carried out by scaling the attractive r-6 term in the Lennard-Jones pair potential by a factor λ ranging from 0 to 1. Liquid-vapor coexistence is observed for all values of λ including λ=0 for Q*=2.0, unlike the corresponding dipolar fluid studied by van Leeuwen and Smit et al. [Phys. Rev. Lett. 71, 3991 (1993)] which showed no phase transition below λ=0.35 when the reduced dipole moment μ*=2.0. The simulation data are analyzed to estimate the critical properties of the quadrupolar fluid and their dependence on the strength λ of the dispersive force. The critical temperature and pressure show a clear quadratic dependence on λ, while the density is less confidently identified as being linear in λ. The compressibility is roughly linear in λ.

  20. Resonant spectra of quadrupolar anions

    NASA Astrophysics Data System (ADS)

    Fossez, K.; Mao, Xingze; Nazarewicz, W.; Michel, N.; Garrett, W. R.; Płoszajczak, M.

    2016-09-01

    In quadrupole-bound anions, an extra electron is attached at a sufficiently large quadrupole moment of a neutral molecule, which is lacking a permanent dipole moment. The nature of the bound states and low-lying resonances of such anions is of interest for understanding the threshold behavior of open quantum systems in general. In this work, we investigate the properties of quadrupolar anions as halo systems, the formation of rotational bands, and the transition from a subcritical to supercritical electric quadrupole moment. We solve the electron-plus-rotor problem using a nonadiabatic coupled-channel formalism by employing the Berggren ensemble, which explicitly contains bound states, narrow resonances, and the scattering continuum. The rotor is treated as a linear triad of point charges with zero monopole and dipole moments and nonzero quadrupole moment. We demonstrate that binding energies and radii of quadrupolar anions strictly follow the scaling laws for two-body halo systems. Contrary to the case of dipolar anions, ground-state band of quadrupolar anions smoothly extend into the continuum, and many rotational bands could be identified above the detachment threshold. We study the evolution of a bound state of an anion as it dives into the continuum at a critical quadrupole moment and we show that the associated critical exponent is α =2 . Everything considered, quadrupolar anions represent a perfect laboratory for the studies of marginally bound open quantum systems.

  1. Nonresonant photon dressing in spin one quadrupolar systems

    SciTech Connect

    Zhuang, Y.L.

    1992-01-01

    This thesis mainly studied 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. The degeneracy of m[sub [Zeta

  2. Quadrupolar Echo Spectra of the Tunneling CD 3Group

    NASA Astrophysics Data System (ADS)

    Olejniczak, Z.; Detken, A.; Manz, B.; Haeberlen, U.

    Deuteron NMR spectra of both single crystal and powder samples of acetylsalicylic acid-CD 3were measured using the quadrupolar-echo technique. The experiments were done in the temperature range 17-100 K, with a special emphasis on the range 20- 30 K, in which the observable tunneling frequency decreases rapidly from its low-temperature value of 2.7 down to 1.2 MHz. In the tunneling regime, modulations of the line intensities and phases as a function of the echo time τ are observed in the single-crystal spectra. The modulation frequency is equal to the orientation-dependent displacement of the inner satellite pairs (α lines) from the Larmor frequency. These effects were confirmed in numerical simulations and fully explain the phase-modulation effects observed previously in quadrupolar-echo spectra of methyl-deuterated methanol and para-xylene guest molecules in some inclusion compounds. By measuring the temperature and orientation dependence of the quadrupolar lineshapes, it was found that the echo spectra are more sensitive to the value of the tunneling frequency than the spectra obtained from the free induction decay. It is pointed out that, because of the modulation effects, special care must be taken when structural parameters are to be extracted from quadrupolar-echo spectra, in particular from spectra of powder samples.

  3. A continuum theory of solvation in quadrupolar solvents. I. Formulation

    NASA Astrophysics Data System (ADS)

    Jeon, Jonggu; Kim, Hyung J.

    2003-10-01

    A continuum theory to describe equilibrium and nonequilibrium solvation in polarizable, nondipolar, quadrupolar solvents is developed. By employing the densities of the solvent quadrupole and induced dipole moments as primary field variables, a reaction field theory formulation for quadrupolar solvents is constructed with account of their electronic polarizability. Nonequilibrium solvation aspects are effected via the solvent coordinate description for the quadrupole moment density. It is found that the theory is consistent with the macroscopic Maxwell equations and satisfies the continuity of the electric potential across the cavity boundaries. Solvation stabilization arising from the solvent quadrupoles is captured via novel reaction field factors analogous to those for dipolar solvents. Comparison is made with the dielectric continuum description of the polarizable, dipolar solvents as well as with previous theories of the quadrupolar solvents. Extensions and applications of the current theoretical formulation to study free energetics and dynamics of reactive and spectroscopic processes in the quadrupolar solvents are reported in the following paper [J. Jeon and H. J. Kim, J. Chem. Phys. 119, 8626 (2003)].

  4. Quadrupolar Interactions in Praseodymium - SILVER(1 - Copper(x)

    NASA Astrophysics Data System (ADS)

    Gotaas, James Alan

    We have utilized magnetization, specific heat, resistivity and diffraction experiments (each as a function of applied magnetic field and temperature) to investigate the magnetic properties of the series of pseudo-binary rare earth-intermetallic compounds PrAg(,1-x)Cu(,x) (for x = 0, 0.15, 0.25, 0.35, 0.4, 0.5, 0.75 and 1.0). For 0 <= x <= 0.4, the samples possess a CsCl -type (cubic) crystal structure and exhibit antiferromagnetic ordering at low temperatures (T(,N) < 11K), as revealed by x-ray and neutron diffraction and magnetization measurements. For x = 0.75 and 1.0, the crystal structure is FeB-type (orthorhombic) and no magnetic ordering occurs for T > 2K. For x = 0.5, the sample undergoes a structural transition from CsCl - to FeB-type upon cooling below 160K. Analysis of magnetization measurements reveals that, in addition to the typical bilinear exchange interactions, the CsCl-type compounds also possess effective negative quadrupolar interactions which increase in magnitude by a factor of five as x increases from 0 to 0.4. Such negative (antiferroquadropolar) interactions favor quadrature alignment of neighboring quadrupoles. Specific heat and resistivity measurements indicate that the magnetic order-disorder transition for x = 0 is a typical antiferromagnetic-paramagnetic transition, displaying a sharp peak in C(,m) vs T and a well-defined spin-disorder contribution to the resistivity. As x increases, however, the peak in the magnetic specific heat broadens and decreases in magnitude, accompanied by a change in the rate of development of entropy and a change in the nature of the magnetic excitations in the ordered state. In addition, the change in the resistivity at the magnetic transition becomes more gradual, and the apparent spin-disorder terms becomes a factor of four smaller. The effective quadrupolar interactions in these systems linked to incipient structural instabilities in the CsCl-type structure which ultimately lead to the structural

  5. The Effect of Magnetic Field Inhomogeneity on the Transverse Relaxation of Quadrupolar Nuclei Measured by Multiple Quantum Filtered NMR

    NASA Astrophysics Data System (ADS)

    Eliav, U.; Kushnir, T.; Knubovets, T.; Itzchak, Y.; Navon, G.

    1997-09-01

    The effects of magnetic fieldsB0andB1inhomogeneities on techniques which are commonly used for the measurements of triple-quantum-filtered (TQF) NMR spectroscopy of23Na in biological tissues are analyzed. The results of measurements by pulse sequences with and without refocusing ofB0inhomogeneities are compared. It is shown that without refocusing the errors in the measurement of the transverse relaxation times by TQF NMR spectroscopy may be as large as 100%, and thus, refocusing of magnetic field inhomogeneity is mandatory. Theoretical calculations demonstrate that without refocusingB0inhomogeneities the spectral width and phase depend on the interpulse time intervals, thus, leading to errors in the measured relaxation times. It is shown that pulse sequences that were used for the refocusing of the magnetic field (B0) inhomogeneity also reduce the sensitivity of the experimental results to radiofrequency (B1) magnetic field inhomogeneity.

  6. Understanding Earth's Albedo Effect

    ERIC Educational Resources Information Center

    Fidler, Chuck

    2012-01-01

    Earth and space science in the middle school classroom are composed of intricately intertwined sets of conceptual systems (AAAS 1993; NRC 1996). Some systems of study, such as the water and rock cycles, are quite explicit and often found as stand-alone middle school science units. Other phenomena are not so apparent, yet they play an extremely…

  7. Understanding Earth's Albedo Effect

    ERIC Educational Resources Information Center

    Fidler, Chuck

    2012-01-01

    Earth and space science in the middle school classroom are composed of intricately intertwined sets of conceptual systems (AAAS 1993; NRC 1996). Some systems of study, such as the water and rock cycles, are quite explicit and often found as stand-alone middle school science units. Other phenomena are not so apparent, yet they play an extremely…

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

    SciTech Connect

    Fernandez, Christian; Pruski, Marek

    2011-06-08

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

  9. General quadrupolar statistical anisotropy: Planck limits

    NASA Astrophysics Data System (ADS)

    Ramazanov, S.; Rubtsov, G.; Thorsrud, M.; Urban, F. R.

    2017-03-01

    Several early Universe scenarios predict a direction-dependent spectrum of primordial curvature perturbations. This translates into the violation of the statistical isotropy of cosmic microwave background radiation. Previous searches for statistical anisotropy mainly focussed on a quadrupolar direction-dependence characterised by a single multipole vector and an overall amplitude g*. Generically, however, the quadrupole has a more complicated geometry described by two multipole vectors and g*. This is the subject of the present work. In particular, we limit the amplitude g* for different shapes of the quadrupole by making use of Planck 2015 maps. We also constrain certain inflationary scenarios which predict this kind of more general quadrupolar statistical anisotropy.

  10. Structural Instability and Quadrupolar Interactions in Praseodymium(silver, Copper) and (holmium, Yttrium)copper.

    NASA Astrophysics Data System (ADS)

    Abu-Aljarayesh, Ibrahim Othman

    In this thesis research, studies were made of the quadrupolar interactions and the structural instabilities in two rare-earth intermetallic systems, PrAg(,1-x)Cu(,x) and Ho(,1-x)Y(,x)Cu. Pair-binding potentials of the Lennard-Jones-type were determined for PrAg(,0.5)Cu(,0.5) by minimizing its binding energy with respect to the seven structural parameters of its low-temperature phase (orthorhombic FeB-type). The potentials determined were used to calculate the dynamical matrix for the higher-temperature phase (cubic CsCl-type) of PrAg(,0.5)Cu(,0.5), from which the phonon dispersion curves along the principal cubic axis were generated. The calculated TA(,1) (C(,44)) phonon mode at the zone-boundary ( 1/2 1/2 0) point was seen to soften progressively as x-increases, which is consistent with the strong negative quadrupolar coupling found in cubic PrAg(,1-x)Cu(,x). Ultrasonic measurements on polycrystalline samples of PrAg and PrAg(,0.6)Cu(,0.4) were also carried out. The effective elastic constant for transverse vibration relative to that for longitudinal vibration was found to be considerably smaller in the latter compound, which indicates a weakening of the elastic constant C(,44) pertinent to the TA(,1) mode with increasing Cu -concentration. Detailed magnetization measurements were carried out on the Ho(,1-x)Y(,x)Cu system. Crystal-field analysis of the magnetization data in the paramagnetic regime disclosed the existence of a negative quadrupolar coupling, which increases steadily in strength as x increases, while the bilinear exchange decreases rapidly. Consistent with the possibility of a growing lattice instability, these changes were seen to continue until, at x > 0.9, a transformation takes place upon cooling from the cubic (CsCl-type) to the orthorhombic (FeB-type) structure. This transformation was first seen by resistivity measurements and later confirmed by neutron diffraction data on YCu.

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

    PubMed

    Bonk, F A; deAzevedo, E R; Sarthour, R S; Bulnes, J D; Freitas, J C C; Guimarães, A P; Oliveira, I S; Bonagamba, T J

    2005-08-01

    This article presents the realization of many self-reversible quantum logic gates using two-qubit quadrupolar spin 3/2 systems. Such operations are theoretically described using propagation matrices for the RF pulses that include the effect of the quadrupolar evolution during the pulses. Experimental demonstrations are performed using a generalized form of the recently developed method for quantum state tomography in spin 3/2 systems. By doing so, the possibility of controlling relative phases of superimposed pseudo-pure states is demonstrated. In addition, many aspects of the effect of the quadrupolar evolution, occurring during the RF pulses, on the quantum operations performance are discussed. Most of the procedures presented can be easily adapted to describe selective pulses of higher spin systems (>3/2) and for spin 1/2 under J couplings.

  12. Resonant Auger for the detection of quadrupolar transitions

    SciTech Connect

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

    2003-01-24

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

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

    PubMed

    Perras, Frédéric A; Bryce, David L

    2014-05-01

    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.

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

    PubMed

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

    2016-05-15

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

  15. Morphological model for quadrupolar δ sunspots

    NASA Astrophysics Data System (ADS)

    Takizawa, K.; Kitai, R.

    2014-12-01

    Sunspot with umbrae of opposite polarity within a single common penumbra are called δ-spot group (Kunzel, 1960). It has been well known that major flares almost always occur in active region with δ-configuration. Hence, to investigate the formation and evolution of δ-configuration is a key in understanding the major flare activities. However, for the case of δ-spot, emerging flux regions (EFRs) combine intricately to each other. Therefore it is so difficult to decipher the relations between multiple EFRs. To clearly follow the development of the ARs, we should select the ARs which can be observed from the initial emerging stage. Emergence and magnetic evolution of solar active regions (ARs) of βγδ-type, which are known to be highly flare active (Sammis 2000), were studied with the SOHO/MDI data in the solar cycle 23. 31 ARs, which can be seen from the birth phase, were selected as unbiased samples of our study. From our analysis, we found that successive birth of two emerging flux regions, spatially separated to each other in east-west direction as a series, forming a quadrupolar magnetic configuration, is a typical way of initial development of βγδ regions. The δ-configuration was formed by following polarity of western EFR with preceding polarity of eastern EFR. We found 11ARs of quadrupolar type among the sampled 31 ARs. In this work, we propose a plausible model for the quadrupolar type δ-spots as a simple magnetic tube of helical structure, which have downward knot in the mid portion of the flux tube. In nine cases out of 11, the characteristics of the magnetic helicity signs, i.e. the signs of twist and writhe, are consistent with our model.

  16. Field-induced quadrupolar quantum criticality in PrV2Al20

    NASA Astrophysics Data System (ADS)

    Shimura, Yasuyuki; Tsujimoto, Masaki; Zeng, Bin; Balicas, Luis; Sakai, Akito; Nakatsuji, Satoru

    2015-06-01

    PrV2Al20 is a heavy-fermion superconductor based on the cubic Γ3 doublet that exhibits nonmagnetic quadrupolar ordering below ˜0.6 K. Our magnetotransport study on PrV2Al20 reveals field-induced quadrupolar quantum criticality at μ0Hc˜11 T applied along the [111] direction. Near the critical field μ0Hc required to suppress the quadrupolar state, we find a marked enhancement of the resistivity ρ (H ,T ) , a divergent quasiparticle effective mass and concomitant non-Fermi-liquid (NFL) behavior [i.e., ρ (T ) ∝Tn with n ≤0.5 ]. We also observe the Shubnikov-de Haas effect above μ0Hc , indicating effective mass enhancement or m*/m0˜10 . This reveals the competition between the nonmagnetic Kondo effect and the intersite quadrupolar coupling which leads to pronounced NFL behavior in an extensive region of T and μ0H emerging from the quantum-critical point.

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

    SciTech Connect

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

    1991-07-01

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

  18. Gravitational quadrupolar coupling and center of gravity: application for Drag-Free Satellites

    NASA Astrophysics Data System (ADS)

    Guilherme, M. S.; Theil, S.

    The motivation of this work is the refinement of modelling of a Drag-Free Satellite DFS for improvement of the disturbance reduction system a so called Drag-Free Control DFC and for the improvement of the data analysis Drag-Free Satellites are missions on fundamental physics as well as geodesy They measure accelerations on a very small scale Especially for the satellites planned for fundamental physics the level of acceleration to be measured is in the range of 10e-15 to 10e-18 m s 2 Because of that any disturbance and misalignment should be modelled Due to the gravity gradient for most extended bodies the center of gravity deviates from the center of mass This results in a gravity gradient torque on satellites as well as on the test masses which depends on the attitude with respect to the gravity gradient In addition the gravity force is also attitude dependent This paper describes this gravity gradient force acting on arbitrary bodies for higher orders of the inertia moments It shows also the influence of the quadrupolar gravitational coupling to the Earth gravity field An equation is developed that determines the center of gravity in the body frame It provides a visualization of the deviation of the center of gravity from the center of mass In order to evaluate the significance of this effects values are computed for several fundamental physicals missions e g GRAVITY PROBE B and STEP

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

    PubMed

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

    2015-11-21

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Nuclear Magnetic Resonance (NMR) relaxation is sensitive to the local structure and dynamics around the probed nuclei. The Electric Field Gradient (EFG) is the key microscopic quantity to understand the NMR relaxation of quadrupolar ions, such as 7Li+, 23Na+, 25Mg2+, 35Cl-, 39K+, or 133Cs+. Using molecular dynamics simulations, we investigate the statistical and dynamical properties of the EFG experienced by alkaline, alkaline Earth, and chloride ions at infinite dilution in water. Specifically, we analyze the effect of the ionic charge and size on the distribution of the EFG tensor and on the multi-step decay of its auto-correlation function. The main contribution to the NMR relaxation time arises from the slowest mode, with a characteristic time on the picosecond time scale. The first solvation shell of the ion plays a dominant role in the fluctuations of the EFG, all the more that the ion radius is small and its charge is large. We propose an analysis based on a simplified charge distribution around the ion, which demonstrates that the auto-correlation of the EFG, hence the NMR relaxation time, reflects primarily the collective translational motion of water molecules in the first solvation shell of the cations. Our findings provide a microscopic route to the quantitative interpretation of NMR relaxation measurements and open the way to the design of improved analytical theories for NMR relaxation for small ionic solutes, which should focus on water density fluctuations around the ion.

  1. Detecting supernovae neutrino with Earth matter effect

    NASA Astrophysics Data System (ADS)

    Liao, Wei

    2016-12-01

    We study Earth matter effect in oscillations of supernovae neutrinos. We show that detecting Earth matter effect gives an independent measurement of spectra of supernovae neutrinos, i.e., the flavor difference of the spectra of supernovae neutrinos. We study the effect of energy resolution and angular resolution of a final electron or positron on detecting the signal of Earth matter effect. We show that varying the widths of energy bins in analysis can change the signal strength of Earth matter effect and the statistical fluctuation. A reasonable choice of energy bins can both suppress the statistical fluctuation and make a good signal strength relative to the statistical fluctuation. Neutrino detectors with good energy resolution and good angular resolution are therefore preferred so that there is more freedom to vary energy bins and to optimize the signal of Earth matter effect in analyzing events of supernovae neutrinos.

  2. Geophysical Effects of the Earth's Monthly Motion

    NASA Astrophysics Data System (ADS)

    Sidorenkov, N. S.; Zhigailo, T. S.

    The generation of a lunar tidal force is a major geophysical effect of the Earth's monthly motion.It is shown that synoptic processes vary simultaneously with tidal oscillations of the Earth's rotation rate and weather exhibits changes near their extremes, i.e., when the Earth is in certain positions on its monthly orbit.It is found that the quasi-biennial oscillation of the wind direction in the equatorial stratosphere is a combined oscillation caused by three periodic processes experienced by the atmosphere: (a) lunisolar tides, (b) the precession of the orbit of the Earth's monthly rotation around the barycenter of the Earth-Moon system, and (c) the motion of the perigee of this orbit.Interference of the 1.20-year Chandler wobble with sidereal, anomalistic, and synodic lunar oscillations gives rise to beats, i.e., to slow periodic variations in the wobble amplitude with periods of 32 to 51 years.

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

    SciTech Connect

    Gann, Sheryl Lee

    1995-11-01

    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 π-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° $\\parallel$ 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 (VEFCP), is presented, along with experimental work on adamantane and polycarbonate.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    SciTech Connect

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

    1989-01-18

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

  6. Kn 26, a new quadrupolar planetary nebula

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    DOE PAGES

    Perras, Frederic A.

    2015-12-15

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

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

    SciTech Connect

    Perras, Frederic A.

    2015-12-15

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

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

    SciTech Connect

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

    2015-11-21

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

  10. 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(SO4)2.12H2O.

    PubMed

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

    2005-04-01

    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(SO4)2.12H2O), recorded in the temperature range from -76 to 92 degrees 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 degrees 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.

  11. 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)

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

    2005-04-01

    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.

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

    ERIC Educational Resources Information Center

    Patil, S. H.

    2009-01-01

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

  13. Efficient prediction of thermodynamic properties of quadrupolar fluids from simulation of a coarse-grained model: the case of carbon dioxide.

    PubMed

    Mognetti, B M; Yelash, L; Virnau, P; Paul, W; Binder, K; Müller, M; MacDowell, L G

    2008-03-14

    Monte Carlo simulations are presented for a coarse-grained model of real quadrupolar fluids. Molecules are represented by particles interacting with Lennard-Jones forces plus the thermally averaged quadrupole-quadrupole interaction. The properties discussed include the vapor-liquid coexistence curve, the vapor pressure along coexistence, and the surface tension. The full isotherms are also accessible over a wide range of temperatures and densities. It is shown that the critical parameters (critical temperature, density, and pressure) depend almost linearly on a quadrupolar parameter q=Q(*4)T*, where Q* is the reduced quadrupole moment of the molecule and T* the reduced temperature. The model can be applied to a variety of small quadrupolar molecules. We focus on carbon dioxide as a test case, but consider nitrogen and benzene, too. Experimental critical temperature, density, and quadrupolar moment are sufficient to fix the parameters of the model. The resulting agreement with experiments is excellent and marks a significant improvement over approaches which neglect quadrupolar effects. The same coarse-grained model was also applied in the framework of perturbation theory in the mean spherical approximation. As expected, the latter deviates from the Monte Carlo results in the critical region, but is reasonably accurate at lower temperatures.

  14. 127I NMR study of quadrupolar echoes in KI

    NASA Astrophysics Data System (ADS)

    Lee, Nelson; Sanctuary, B. C.; Halstead, T. K.

    Potassium iodide (K 121I), like KBr and many other alkali halide solids, has cubic symmetry. Distortion of this cubic symmetry in single crystals of KI creates electric field gradients of sufficient strength for the quadrupolar interactions to dominate the dynamics of the system. Simple one-, two-, and three-pulse sequences applied to such crystals permit the observation, in the time domain, of the solid- or quadrupolar-echo phenomenon for spin I = {5}/{2}( 127I) . Using the multipole approach to interpret the experimental responses of three-pulse sequences, the characteristic relaxation behavior of the first-, second-, third-, and fifth-rank zero- and multiquantum polarizations are determined. The experimental determination of distinct relaxation times for the higher rank polarizations in both KI and KBr ( I = {3}/{2}) lends credibility to the concept of the multipoles as physical quantities.

  15. Two-dimensional nuclear magnetic resonance of quadrupolar systems

    SciTech Connect

    Wang, Shuanhu

    1997-09-01

    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.

  16. Population transfer HMQC for half-integer quadrupolar nuclei

    SciTech Connect

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

    2015-03-07

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

  17. Using the dipolar and quadrupolar moments to improve solar-cycle predictions based on the polar magnetic fields.

    PubMed

    Muñoz-Jaramillo, Andrés; Balmaceda, Laura A; DeLuca, Edward E

    2013-07-26

    The solar cycle and its associated magnetic activity are the main drivers behind changes in the interplanetary environment and Earth's upper atmosphere (commonly referred to as space weather and climate). In recent years there has been an effort to develop accurate solar cycle predictions, leading to nearly a hundred widely spread predictions for the amplitude of solar cycle 24. Here we show that cycle predictions can be made more accurate if performed separately for each hemisphere, taking advantage of information about both the dipolar and quadrupolar moments of the solar magnetic field during minimum.

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

    PubMed

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

    2012-03-01

    The observation of a double-quantum filtered signal of quadrupolar nuclei (e.g. (23)Na) in solution has been traditionally interpreted as a sign for anisotropic reorientational motion. Ling and Jerschow (2007) have found that a (23)Na double-quantum signal is observed also in solutions of TmDOTPNa(5). Interference effects between the quadrupolar and the paramagnetic interactions have been reported to lead to the appearance of double-quantum coherences even in the absence of a residual quadrupolar interaction. In addition, such processes lead to differential linebroadening effects between the satellite transitions, akin to effects that are well known for dipolar-CSA cross-correlation. Here, we report experiments on sodium in the presence of LnDOTP compounds, where it is shown that these cross-correlation effects correlate well with the pseudo-contact shift. In addition, anisotropic g-values of the lanthanide compounds in question, can also lead to alignment within the magnetic field, and consequently to the appearance of line splitting and double-quantum coherences. The two competing effects are demonstrated and it is concluded that both cross-correlated relaxation and alignment in the magnetic field must be at work in the systems described here. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Earth Sphericity Effects on Subduction Morphology

    NASA Astrophysics Data System (ADS)

    Morra, G.; Chatelain, P.; Tackley, P.; Koumoutsakos, P.

    2007-12-01

    We present here the first application in Geodynamics of a Multipole accelerated Boundary Element Method (FMM- BEM) for Stokes Flow. The approach offers the advantage of a reduced number of computational elements and linear scaling with the problem size. We show that this numerical mehod can be fruitfully applied to the simulation of several geodynamic systems at the planetary scale in spheical coordinates and we suggest a general appraoch for modeling combined mantle convection and plate tectonics. The potentialities of the approach are shown investigating the effect played by Earth sphericity on the subduction of a very wide oceanic lithosphere , comparing the morphology of the subducted lithosphere in a spherical and in flat setting. The results show a striking difference between the two models: while the slab on a "flat Earth" shows slight undulation, the same subducting plate on a spherical Earth-like setting presents a distinct folding below the trench far from the edges, with wavelength of (1000km-2000km) as Pacific trenches.

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

    SciTech Connect

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

    2014-06-15

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

  1. Quinoline-Derived Two-Photon Sensitive Quadrupolar Probes.

    PubMed

    Tran, Christine; Berqouch, Nawel; Dhimane, Hamid; Clermont, Guillaume; Blanchard-Desce, Mireille; Ogden, David; Dalko, Peter I

    2017-02-03

    Quadrupolar probes derived from 8-dimethylamino-quinoline (8-DMAQ) having a pegylated fluorene core were prepared and studied under "one-photon" (λ=365 nm) and "two-photon" (TP) (λ=730 nm) irradiation conditions. Compound 1 a was identified as the most efficient probe by UV activation that showed sequential release of acetic acid as a model. Although the probe showed high two-photon absorption it stayed inert under femtosecond irradiation conditions. Fast and selective photolysis was observed, however, by using picosecond irradiation conditions with a remarkably high TP uncaging cross-section (δu =2.3 GM).

  2. Quantum mechanical identification of quadrupolar plasmonic excited states in silver nanorods

    DOE PAGES

    Gieseking, Rebecca L.; Ratner, Mark A.; Schatz, George C.

    2016-10-27

    Quadrupolar plasmonic modes in noble metal nanoparticles have gained interest in recent years for various sensing applications. Although quantum mechanical studies have shown that dipolar plasmons can be modeled in terms of excited states where several to many excitations contribute coherently to the transition dipole moment, new approaches are needed to identify the quadrupolar plasmonic states. We show that quadrupolar states in Ag nanorods can be identified using the semiempirical INDO/SCI approach by examining the quadrupole moment of the transition density. The main longitudinal quadrupolar states occur at higher energies than the longitudinal dipolar states, in agreement with previous classicalmore » electrodynamics results, and have collective plasmonic character when the nanorods are sufficiently long. In conclusion, the ability to identify these states will make it possible to evaluate the differences between dipolar and quadrupolar plasmons that are relevant for sensing applications.« less

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

    PubMed

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

    2009-12-01

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

  4. Quantum mechanical identification of quadrupolar plasmonic excited states in silver nanorods

    SciTech Connect

    Gieseking, Rebecca L.; Ratner, Mark A.; Schatz, George C.

    2016-10-27

    Quadrupolar plasmonic modes in noble metal nanoparticles have gained interest in recent years for various sensing applications. Although quantum mechanical studies have shown that dipolar plasmons can be modeled in terms of excited states where several to many excitations contribute coherently to the transition dipole moment, new approaches are needed to identify the quadrupolar plasmonic states. We show that quadrupolar states in Ag nanorods can be identified using the semiempirical INDO/SCI approach by examining the quadrupole moment of the transition density. The main longitudinal quadrupolar states occur at higher energies than the longitudinal dipolar states, in agreement with previous classical electrodynamics results, and have collective plasmonic character when the nanorods are sufficiently long. In conclusion, the ability to identify these states will make it possible to evaluate the differences between dipolar and quadrupolar plasmons that are relevant for sensing applications.

  5. QUEST-QUadrupolar Exact SofTware: a fast graphical program for the exact simulation of NMR and NQR spectra for quadrupolar nuclei.

    PubMed

    Perras, Frédéric A; Widdifield, Cory M; Bryce, David L

    2012-01-01

    We present a new program for the exact simulation of solid-state NMR spectra of quadrupolar nuclei in stationary powdered samples which employs diagonalization of the combined Zeeman-quadrupolar Hamiltonian. The program, which we call QUEST (QUadrupolar Exact SofTware), can simulate NMR spectra over the full regime of Larmor and quadrupolar frequency ratios, which encompasses scenarios ranging from high-field NMR to nuclear quadrupole resonance (NQR, where the Larmor frequency is zero) and does not make use of approximations when treating the quadrupolar interaction. With the use of the fast powder averaging scheme of Alderman, Solum, and Grant, exact NMR spectral simulations are only marginally slower than the second-order perturbation theory counterpart. The program, which uses a graphical user interface, also incorporates chemical shift anisotropy and non-coincident chemical shift and quadrupolar tensor frames. The program is validated against newly-acquired experimental data through several examples including: the low-field (79/81)Br NMR spectra of CaBr(2), the (14)N overtone NMR spectrum of glycine, the (187)Re NQR spectra of Re(2)(CO)(10), and lastly the (127)I overtone NQR spectrum of SrI(2), which, to the best of our knowledge, represents the first direct acquisition of an overtone NQR spectrum for a powdered sample. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Earth radiation pressure effects on satellites

    NASA Technical Reports Server (NTRS)

    Knocke, P. C.; Ries, J. C.; Tapley, B. D.

    1988-01-01

    A diffuse-earth radiation force model is presented, which includes a latitudinally varying representation of the shortwave and longwave radiation of the terrestrial sphere. Applications to various earth satellites indicate that this force, in particular the shortwave component, can materially affect the recovery of estimated parameters. Earth radiation pressure cannot explain the anomalous deceleration of LAGEOS, but can produce significant along track accelerations on satellites with highly eccentric orbits. Analyses of GEOS-1 tracking data confirm this result.

  7. Quadrupolar relaxation of hyperpolarized krypton-83 as a probe for surfaces.

    PubMed

    Stupic, Karl F; Cleveland, Zackary I; Pavlovskaya, Galina E; Meersmann, Thomas

    2006-02-01

    This work reports the first systematic study of relaxation experienced by the hyperpolarized (hp) noble gas isotope (83)Kr (I=9/2) in contact with surfaces. The spin-lattice relaxation of (83)Kr is found to depend strongly on the chemical composition of the surfaces in the vicinity of the gas. This effect is caused by quadrupolar interactions during brief periods of surface adsorption that are the dominating source of longitudinal spin relaxation in the (83)Kr atoms. Simple model systems of closest packed glass beads with uniform but variable bead sizes are used for the relaxation measurements. The observed relaxation rates depend strongly on the chemical treatment of the glass surfaces and on the surface to volume ratio. Hp (83)Kr NMR relaxation measurements of porous polymers with pore sizes of 70-250 microm demonstrate the potential use of this new technique for material sciences applications.

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

    NASA Astrophysics Data System (ADS)

    Singh, Ram Chandra

    2013-01-01

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

  9. Coronal Magnetic Flux Ropes in Quadrupolar Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Zhang, Yingzhi; Hu, Youqiu; Wang, Jingxiu

    Using a 2.5-D, time-dependent ideal MHD model in spherical coordinates, we carry out a numerical study of the equilibrium properties of coronal magnetic flux ropes in a quadrupolar background magnetic field. For such a flux rope system, a catastrophic occurs: the flux rope is detached from the photosphere and jumps to a finite altitude with a vertical current sheet below. There is a transversal current sheet formed above the rope, and the whole system stays in quasi-equilibrium. We argue that the additional Lorentz force provided by the transversal current sheet on the flux rope plays an important role in keeping the system in quasi-equilibrium in the corona.

  10. Distinguishing magnetic vs. quadrupolar relaxation in b-NMR using 8Li and 9Li

    NASA Astrophysics Data System (ADS)

    Chatzichristos, A.; McFadden, R. M. L.; Karner, V. L.; Cortie, D. L.; Fang, A.; Levy, C. D. P.; Macfarlane, W. A.; Morris, G. D.; Pearson, M. R.; Salman, Z.; Kiefl, R. F.

    2016-09-01

    Beta-detected NMR is a powerful technique in condensed matter physics. It uses the parity violation of beta decay to detect the NMR signal from a beam of highly polarized radionuclides implanted in a sample material. Spin-lattice relaxation (SLR) is studied by monitoring the rate with which the asymmetry between the beta counts in two opposing detectors is lost. Unlike classical NMR, b-NMR can study thin films and near-surface effects. The most common b-NMR isotope at TRIUMF is 8Li, which has a quadrupole moment, thus it is sensitive to both magnetic fields and electric field gradients. A challenge with 8Li b-NMR is identifying the predominant mechanism of SLR in a given sample. It is possible to distinguish between SLR mechanisms by varying the probe isotope. For two isotopes with different nuclear moments, the ratio of SLR rates should be different in the limits of either pure magnetic or quadrupolar relaxation. This method has been used in classical NMR and we report its first application to b-NMR. We measured the SLR rates for 8Li and 8Li in Pt foil and SrTiO3. Pt is a test case for pure magnetic relaxation. SrTiO3 is a non-magnetic insulator, but the source of its relaxation is not well understood. Here we show that its relaxation is mainly quadrupolar. We thank TRIUMF's CMMS for their technical support. This work was supported by: NSERC Discovery Grants to R.F.K. and W.A.M.; and IsoSiM fellowships to A.C. and R.M.L.M.

  11. Effects of spraying rare earths on contents of rare Earth elements and effective components in tea.

    PubMed

    Wang, Dongfeng; Wang, Changhong; Ye, Sheng; Qi, Hongtao; Zhao, Guiwen

    2003-11-05

    Rare earth (RE) fertilizer is widely applied in China to increase the yield and the quality of crops including tea. However, the effects of spraying RE fertilizer on the contents of rare earth elements (REE) and effective components in tea are unknown. The results from basin and field experiments show that the values of the REE concentrations in new shoots of tea plants and the concentration of REE in the soil (REE/REEs) either from control basins or from treatment basins were smaller than those in other parts of tea plant and similar between control and treatment. The longer the interval between spraying RE fertilizer and picking the shoots of tea plants, the less the effects from spraying. About 80% summation operator REE (the sum of the concentrations of 15 REE) in tea, whether it came from spraying or not, was insoluble in the infusion. About 10% the soluble REE of summation operator REE in tea infusion was bound to polysaccharide, and the amount of REE bound polysaccharide decreased over time. At least a 25 day safety interval is needed between spraying and picking if the microelement fertilizer is used, in order to enhance tea output and to ensure tea safety.

  12. Earth

    NASA Image and Video Library

    2012-01-30

    Behold one of the more detailed images of the Earth yet created. This Blue Marble Earth montage shown above -- created from photographs taken by the Visible/Infrared Imager Radiometer Suite (VIIRS) instrument on board the new Suomi NPP satellite -- shows many stunning details of our home planet. The Suomi NPP satellite was launched last October and renamed last week after Verner Suomi, commonly deemed the father of satellite meteorology. The composite was created from the data collected during four orbits of the robotic satellite taken earlier this month and digitally projected onto the globe. Many features of North America and the Western Hemisphere are particularly visible on a high resolution version of the image. http://photojournal.jpl.nasa.gov/catalog/PIA18033

  13. Effects of the tidal mass redistribution on the Earth rotation

    NASA Astrophysics Data System (ADS)

    Baenas, T.; Ferrándiz, J.; Escapa, A.; Getino, J.

    2015-08-01

    The effects of the tidal mass redistributions on the Earth precession and nutations are revisited, under various hypothesis on the elastic response of the Earth and using the Hamiltonian approach. New non-negligible secular and periodic contributions have been found.

  14. Studies of heteronuclear dipolar interactions between spin-1/2 and quadrupolar nuclei by using REDOR during multiple quantum evolution

    NASA Astrophysics Data System (ADS)

    Pruski, M.; Bailly, A.; Lang, D. P.; Amoureux, J.-P.; Fernandez, C.

    1999-06-01

    A new technique for measurements of dipolar interactions in rotating solids is presented that combines the capabilities of multiple quantum magic angle spinning (MQMAS) with the rotational echo double resonance (REDOR). It employs the dipolar recoupling between spin-1/2 ( I) and quadrupolar ( S) nuclei by applying a series of π pulses to the I spins. In contrast to the previously reported MQ-REDOR method, the recoupling sequence is applied during the triple quantum, rather than single quantum evolution. As the dipolar effect is enhanced by the MQ coherence order, this new technique exhibits improved sensitivity toward weak dipolar interactions.

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

    PubMed

    Dib, Eddy; Alonso, Bruno; Mineva, Tzonka

    2014-05-15

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

  16. High radio-frequency field strength nutation NMR of quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Franssen, W. M. J.; Rezus, Y. L. A.; Kentgens, A. P. M.

    2016-12-01

    Owing to the introduction of microcoils, high RF field strength nutation NMR is a viable candidate for the study of quadrupolar nuclei with strong quadrupolar couplings, not accessible using contemporary NMR techniques. We show powder 23 Na nutation spectra on sodium nitrite for RF field strengths of up to 1170 kHz, that conform to theoretical predictions. For lanthanum fluoride powder, 139 La nutation spectra taken at elevated RF field amplitudes show clear discrepancies when compared to the theory. These errors are shown to be mainly caused by pulse transients at the end of the pulse, which proved to be detrimental to the shape of the nutation spectra. Using a nutation pulse which ends in a sudden frequency jump, we show that these errors can be reduced, and nutation spectra that conform to theory can be readily acquired. This enables nutation NMR for the study of quadrupolar nuclei with a strong quadrupolar coupling, bridging the gap between NMR, which can only analyse nuclei with a weak to medium quadrupolar coupling, and NQR, were extensive searching for the right quadrupolar frequency is the limiting factor.

  17. Asymmetric effects on Earth's polar motion

    NASA Astrophysics Data System (ADS)

    Bizouard, Christian; Zotov, Leonid

    2013-06-01

    Differential equations ruling the Earth's polar motion are slightly asymmetric with respect to the pole coordinates. This is not only associated with the lack of axial symmetry around the Earth figure axis (triaxiality) but also with the longitude dependency of the pole tide (the main contribution). We propose a consistent handling of both asymmetric contributions, formulating a unique equation in the complex equatorial plane, of which we derive a general solution. Difference with respect to the usual symmetric solution is discussed and found significant in light of the present accuracy of the observed pole coordinates. For the same geophysical excitation, the prograde Chandler wobble is accompanied by a retrograde component up to 2 milliarcseconds (mas), transforming it in a slight elliptic motion. The asymmetric contribution is relatively larger in the geodetic excitation function, for Chandler wobble excitation mixes prograde and retrograde components of comparable level (1 mas).

  18. Double Catastrophe of Coronal Flux Rope in Quadrupolar Magnetic Field

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Z.; Hu, Y. Q.; Wang, J. X.

    2005-06-01

    Using a relaxation method based on time-dependent ideal magnetohydrodynamic simulations, we find 2.5-dimensional force-free field solutions in spherical geometry, which are associated with an isolated flux rope embedded in a quadrupolar background magnetic field. The background field is of Antiochos type, consisting of a dipolar and an octopolar component with a neutral point somewhere in the equatorial plane. The flux rope is characterized by its magnetic fluxes, including the annular flux Φp and the axial magnetic flux Φϕ, and its geometric features described by the height of the rope axis and the length of the vertical current sheet below the rope. It is found that for a given Φp, the force-free field exhibits a complex catastrophic behavior with respect to increasing Φϕ. There exist two catastrophic points, and the catastrophic amplitude, measured by the jump in the height of the rope axis, is finite for both catastrophes. As a result, the flux rope may levitate stably in the corona after catastrophe, with a transverse current sheet above and a vertical current sheet below. The magnetic energy threshold for the two successive catastrophes are found to be larger than the corresponding partly open field energy. We argue that it is the transverse current sheet formed above the flux rope that provides a downward Lorentz force on the flux rope and thus keeps the rope levitating stably in the corona.

  19. Earth matter effects in detection of supernova neutrinos

    SciTech Connect

    Guo, X.-H.; Young Binglin

    2006-05-01

    We calculated the matter effect, including both the Earth and supernova, on the detection of neutrinos from type II supernovae at the proposed Daya Bay reactor neutrino experiment. It is found that apart from the dependence on the flip probability P{sub H} inside the supernova and the mass hierarchy of neutrinos, the amount of the Earth matter effect depends on the direction of the incoming supernova neutrinos, and reaches the biggest value when the incident angle of neutrinos is around 93 deg. In the reaction channel {nu}{sub e}+p{yields}e{sup +}+n the Earth matter effect can be as big as about 12%. For other detection processes the amount of the Earth matter effect is a few per cent.

  20. Earth matter effects in detection of supernova neutrinos

    NASA Astrophysics Data System (ADS)

    Guo, X.-H.; Young, Bing-Lin

    2006-05-01

    We calculated the matter effect, including both the Earth and supernova, on the detection of neutrinos from type II supernovae at the proposed Daya Bay reactor neutrino experiment. It is found that apart from the dependence on the flip probability PH inside the supernova and the mass hierarchy of neutrinos, the amount of the Earth matter effect depends on the direction of the incoming supernova neutrinos, and reaches the biggest value when the incident angle of neutrinos is around 93°. In the reaction channel ν¯e+p→e++n the Earth matter effect can be as big as about 12%. For other detection processes the amount of the Earth matter effect is a few per cent.

  1. DFT calculations of quadrupolar solid-state NMR properties: Some examples in solid-state inorganic chemistry.

    PubMed

    Cuny, Jerome; Messaoudi, Sabri; Alonzo, Veronique; Furet, Eric; Halet, Jean-François; Le Fur, Eric; Ashbrook, Sharon E; Pickard, Chris J; Gautier, Regis; Le Polles, Laurent

    2008-10-01

    This article presents results of first-principles calculations of quadrupolar parameters measured by solid-state nuclear magnetic measurement (NMR) spectroscopy. Different computational methods based on density functional theory were used to calculate the quadrupolar parameters. Through a series of illustrations from different areas of solid state inorganic chemistry, it is shown how quadrupolar solid-state NMR properties can be tackled by a theoretical approach and can yield structural information.

  2. Diffraction and polarization effects in Earth radiation budget measurements.

    PubMed

    Mahan, J R; Barki, A R; Priestley, K J

    2016-12-01

    Thermal radiation emitted and reflected from the Earth and viewed from near-Earth orbit may be characterized by its spectral distribution, its degree of coherence, and its state of polarization. The current generation of broadband Earth radiation budget instruments has been designed to minimize the effect of diffraction and polarization on science products. We used Monte Carlo ray-trace (MCRT) models that treat individual rays as quasi-monochromatic, polarized entities to explore the possibility of improving the performance of such instruments by including measures of diffraction and polarization during calibration and operation. We have demonstrated that diffraction and polarization sensitivity associated with typical Earth radiation budget instrument design features has a negligible effect on measurements.

  3. Effects of Earth Encounters on the Rotational Properties of Near-Earth Objects

    NASA Astrophysics Data System (ADS)

    Chit Siu, Ho; Keane, James T.; Moskovitz, Nicholas; Binzel, Richard P.

    2015-11-01

    The effects of Earth encounters on the physical properties of near-Earth objects (NEOs) have been shown to be significant factors in their evolution. Previous studies have examined the effects of these encounters on reflectance spectra, and effects such as spin state and shape changes have been studied for specific asteroids and through simulation. In this study, archive data from previous NEO surveys were used to investigate rotational frequencies as a function of minimum orbit intersection distance (MOID), which we use as a proxy for Earth encounter likelihood.When comparing objects of similar sizes, we find a highly significant difference in the dispersion of rotational frequency (p < 0.01; significant at a >99% confidence level) between NEO populations that were likely to have had an Earth encounter and those that are less likely to have had such an encounter. The encounter/non-encounter distinction is found at a dividing MOID value of 1 lunar distance (LD). These results were robust to changes in the size of the moving average window, as well as to removal of the smallest objects from the encounter population and the largest objects from the non-encounter population, which would be most strongly affected by a known size/spin period bias where smaller objects tend to have shorter periods. There was no statistically significant difference in the mean rotation rates of encounter and non-encounter objects, however, indicating that encounters cause greater dispersion, but do not preferentially spin objects up or down at a detectable level. Recent modeling work also lends credibility to the idea that NEO interactions with the Earth-Moon system as a whole may be leading to the dispersion difference boundary at 1 LD (Keane et al. 2015, DPS).

  4. XMCD investigation of Rare Earth Metal at high pressure conditions

    NASA Astrophysics Data System (ADS)

    Nataf, Lucie; Baudelet, Francois

    2013-06-01

    The X-ray Magnetic Circular Dichroism is a selective magnetic probe for high pressure studies. Nowadays, XMCD under pressure is usually employed, mainly on 3d and 5d metal systems. We will present new results on Rare Earth metals. Up to now, most of the pressure works are devoted to the structural properties of RE. However, only a few works deal with the pressure effect on their magnetic properties. RE, having high magnetic moment and large anisotropy, are commonly used for practical applications. Nevertheless, their magnetic ordering temperature is below RT. Adding transition metals solves this limitation: the alloys then present the advantages of RE and the high magnetic ordering temperature of TM. To optimize the properties of these systems, a pressure study may be a better way than an empirical investigation. Interpreting the XMCD signal at the L2,3 edges of RE is very difficult since many contributions are involved. The important role of the 4f-5d interactions has to be taken into account and the quadrupolar transitions cannot be neglected. The quadrupolar transitions can be of the same order than the dipolar ones, since the 4f orbitals carry a much larger spin and orbital moments than the 5d. Under compression, each orbital may not been affected in the same way, thus giving rise to a separation of the dipolar and quadrupolar contributions and a better understanding of these signals. Among the few works dedicated to the magnetic properties of RE under pressure, it has been shown that metallic Dysprosium is no more magnetic above 7.5 GPa. Our XMCD measurements contradict this result since a signal is still observed.

  5. Solid state nuclear magnetic resonance studies of cross polarization from quadrupolar nuclei

    SciTech Connect

    De Paul, Susan M.

    1997-08-01

    The development of solid-state Nuclear Magnetic Resonance (NMR) has, to a large extent, focused on using spin-1/2 nuclei as probes to investigate molecular structure and dynamics. For such nuclei, the technique of cross polarization is well-established as a method for sensitivity enhancement. However, over two-thirds of the nuclei in the periodic table have a spin-quantum number greater than one-half and are known as quadrupolar nuclei. Such nuclei are fundamental constituents of many inorganic materials including minerals, zeolites, glasses, and gels. It is, therefore, of interest to explore the extent to which polarization can be transferred from quadrupolar nuclei. In this dissertation, solid-state NMR experiments involving cross polarization from quadrupolar nuclei to spin-1/2 nuclei under magic-angle spinning (MAS) conditions are investigated in detail.

  6. Reconnection Guide Field and Quadrupolar Structure Observed by MMS on 16 October 2015 at 1307 UT

    NASA Technical Reports Server (NTRS)

    Denton, R. E.; Sonnerup, B. U. O.; Hasagawa, H.; Phan, T. D.; Russell, C. T.; Strangeway, R. J.; Giles, B. L.; Torbert, R. B.

    2016-01-01

    We estimate the guide field near the X point, B(sub M0), for a magnetopause crossing by the Magnetospheric Multiscale (MMS) spacecraft at 1307 UT on 16 October 2015 that showed features of electron-scale reconnection. This component of the magnetic field is normal to the reconnection plane L-N containing the reconnection magnetic field, B(sub L), and the direction e(sub N) normal to the current sheet. The B(sub M) field component appears to approximately have quadrupolar structure close to the X point. Using several different methods to estimate values of the guide field near the X point, some of which use an assumed quadrupolar symmetry, we find values ranging between -3.1 nT and -1.2 nT, with a nominal value of about -2.5 nT. The rough consistency of these values is evidence that the quadrupolar structure exists.

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

    PubMed

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

    2015-09-21

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

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

    SciTech Connect

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

    2015-08-04

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

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

    DOE PAGES

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

    2015-08-04

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

  10. Instability of some divalent rare earth ions and photochromic effect

    NASA Astrophysics Data System (ADS)

    Egranov, A. V.; Sizova, T. Yu.; Shendrik, R. Yu.; Smirnova, N. A.

    2016-03-01

    It was shown that the divalent rare earth ions (La, Ce, Gd, Tb, Lu, and Y) in cubic sites in alkaline earth fluorides are unstable with respect to electron autodetachment since its d1(eg) ground state is located in the conduction band which is consistent with the general tendency of these ions in various compounds. The localization of doubly degenerate d1(eg) level in the conduction band creates a configuration instability around the divalent rare earth ion that leading to the formation of anion vacancy in the nearest neighborhood, as was reported in the previous paper [A. Egranov, T. Sizova, Configurational instability at the excited impurity ions in alkaline earth fluorites, J. Phys. Chem. Solids 74 (2013) 530-534]. Thus, the formation of the stable divalent ions as La, Ce, Gd, Tb, Lu, and Y (PC+ centers) in CaF2 and SrF2 crystals during x-ray irradiation occurs via the formation of charged anion vacancies near divalent ions (Re2+va), which lower the ground state of the divalent ion relative to the conductivity band. Photochromic effect occurs under thermally or optically stimulated electron transition from the divalent rare earth ion to the neighboring anion vacancy and reverse under ultraviolet light irradiation. It is shown that the optical absorption of the PC+ centers due to d → d and d → f transitions of the divalent rare-earth ion.

  11. Virtual Earth System Laboratory (VESL): Effective Visualization of Earth System Data and Process Simulations

    NASA Astrophysics Data System (ADS)

    Quinn, J. D.; Larour, E. Y.; Cheng, D. L. C.; Halkides, D. J.

    2016-12-01

    The Virtual Earth System Laboratory (VESL) is a Web-based tool, under development at the Jet Propulsion Laboratory and UC Irvine, for the visualization of Earth System data and process simulations. It contains features geared toward a range of applications, spanning research and outreach. It offers an intuitive user interface, in which model inputs are changed using sliders and other interactive components. Current capabilities include simulation of polar ice sheet responses to climate forcing, based on NASA's Ice Sheet System Model (ISSM). We believe that the visualization of data is most effective when tailored to the target audience, and that many of the best practices for modern Web design/development can be applied directly to the visualization of data: use of negative space, color schemes, typography, accessibility standards, tooltips, etc cetera. We present our prototype website, and invite input from potential users, including researchers, educators, and students.

  12. Multiple-quantum cross-polarization in MAS NMR of quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Ashbrook, Sharon E.; Brown, Steven P.; Wimperis, Stephen

    1998-05-01

    Using 27Al ( I=5/2) NMR of aluminium acetylacetonate, we show that it is possible to cross-polarize from a spin I=1/2 nucleus ( 1H) directly to the central triple-quantum transition of a half-integer quadrupolar nucleus ( 27Al) in a powdered sample under MAS conditions. The optimum conditions for this multiple-quantum cross-polarization (MQCP) are investigated experimentally and compared with existing theoretical results. The new technique is applied to the recently introduced two-dimensional MQMAS experiment for recording high-resolution NMR spectra of half-integer quadrupolar nuclei.

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

    PubMed

    Semchyschyn, Darlene J; Macdonald, Peter M

    2004-02-01

    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

  14. Propagation Effects in Space/Earth Paths.

    DTIC Science & Technology

    1980-08-01

    staff and other collaborators. H.J.ALBRECHT Editor &COeSsioi or- XTIS GRPA.I TDC TAB LVve ounc ed Justification Di t ribut’i / .li /vfl.,Q4."s Codes...SOLUTIONS by E.Baha and B.S.Agrawal 24 1979-1980 DATA PROCESSING AND RESULTS FROM THE OTS BEACONS BO/B I AND TM , AND RADIOMETRY AT 11.4 AND 35 GHz by...scatterers, neglecting high order scattering 1 4 may be written: a(dB) =[1/(l-w)]10 log [ Tm /( Tm -TA)] where w is the scattering albedo and Tm the effective

  15. Understanding and prediction of electronic-structure-driven physical behaviors in rare-earth compounds.

    PubMed

    Paudyal, Durga; Pathak, Arjun K; Pecharsky, V K; Gschneidner, K A

    2013-10-02

    Rare-earth materials, due to their unique magnetic properties, are important for fundamental and technological applications such as advanced magnetic sensors, magnetic data storage, magnetic cooling and permanent magnets. For an understanding of the physical behaviors of these materials, first principles techniques are one of the best theoretical tools to explore the electronic structure and evaluate exchange interactions. However, first principles calculations of the crystal field splitting due to intra-site electron-electron correlations and the crystal environment in the presence of exchange splitting in rare-earth materials are rarely carried out despite the importance of these effects. Here we consider rare-earth dialuminides as model systems and show that the low temperature anomalies observed in these systems are due to the variation of both exchange and crystal field splitting leading to anomalous intra-site correlated-4f and itinerant-5d electronic states near the Fermi level. From calculations supported by experiments we uncover that HoAl2 is unique among rare-earth dialuminides, in that it undergoes a cubic to orthorhombic distortion leading to a spin reorientation. Calculations of a much more extended family of mixed rare-earth dialuminides reveal an additional degree of complexity: the effective quadrupolar moment of the lanthanides changes sign as a function of lanthanide concentration, leading to a change in the sign of the anisotropy constant. At this point the quadrupolar interactions are effectively reduced to zero, giving rise to lattice instability and leading to new phenomena. This study shows a clear picture that accurate evaluation of the exchange, crystal field splitting and shape of the charge densities allows one to understand, predict and control the physical behaviors of rare-earth materials.

  16. The Runaway Greenhouse Effect on Earth and other Planets

    NASA Technical Reports Server (NTRS)

    Rabbette, Maura; Pilewskie, Peter; McKay, Christopher; Young, Robert

    2001-01-01

    Water vapor is an efficient absorber of outgoing longwave infrared radiation on Earth and is the primary greenhouse gas. Since evaporation increases with increasing sea surface temperature, and the increase in water vapor further increases greenhouse warming, there is a positive feedback. The runaway greenhouse effect occurs if this feedback continues unchecked until all the water has left the surface and enters the atmosphere. For Mars and the Earth the runaway greenhouse was halted when water vapor became saturated with respect to ice or liquid water respectively. However, Venus is considered to be an example of a planet where the runaway greenhouse effect did occur, and it has been speculated that if the solar luminosity were to increase above a certain limit, it would also occur on the Earth. Satellite data acquired during the Earth Radiation Budget Experiment (ERBE) under clear sky conditions shows that as the sea surface temperature (SST) increases, the rate of outgoing infrared radiation at the top of the atmosphere also increases, as expected. Over the pacific warm pool where the SST exceeds 300 K the outgoing radiation emitted to space actually decreases with increasing SST, leading to a potentially unstable system. This behavior is a signature of the runaway greenhouse effect on Earth. However, the SST never exceeds 303K, thus the system has a natural cap which stops the runaway. According to Stefan-Boltzmann's law the amount of heat energy radiated by the Earth's surface is proportional to (T(sup 4)). However, if the planet has a substantial atmosphere, it can absorb all infrared radiation from the lower surface before the radiation penetrates into outer space. Thus, an instrument in space looking at the planet does not detect radiation from the surface. The radiation it sees comes from some level higher up. For the earth#s atmosphere the effective temperature (T(sub e)) has a value of 255 K corresponding to the middle troposphere, above most of the

  17. The effects of general relativity on near-earth satellites

    NASA Technical Reports Server (NTRS)

    Ries, J. C.; Watkins, M. M.; Tapley, B. D.; Huang, C.

    1990-01-01

    Whether one uses a solar system barycentric frame or a geocentric frame when including the general theory of relativity in orbit determination for near-earth satellites, the results should be equivalent to some limiting accuracy. The purpose of this paper is to clarify the effects of relativity in each frame and to demonstrate their equivalence through the analysis of three years of laser tracking data taken on the Lageos satellite. It is demonstrated that the simpler formulation in the geocentric frame is adequate for the purpose of near-earth satellite orbit determination. A correction to the conventional barycentric equations of motion is shown to be required.

  18. The effects of general relativity on near-earth satellites

    NASA Technical Reports Server (NTRS)

    Ries, J. C.; Watkins, M. M.; Tapley, B. D.; Huang, C.

    1990-01-01

    Whether one uses a solar system barycentric frame or a geocentric frame when including the general theory of relativity in orbit determination for near-earth satellites, the results should be equivalent to some limiting accuracy. The purpose of this paper is to clarify the effects of relativity in each frame and to demonstrate their equivalence through the analysis of three years of laser tracking data taken on the Lageos satellite. It is demonstrated that the simpler formulation in the geocentric frame is adequate for the purpose of near-earth satellite orbit determination. A correction to the conventional barycentric equations of motion is shown to be required.

  19. The Runaway Greenhouse Effect on Earth and other Planets

    NASA Technical Reports Server (NTRS)

    Rabbette, Maura; Pilewskie, Peter; McKay, Christopher; Young, Robert

    2001-01-01

    Water vapor is an efficient absorber of outgoing longwave infrared radiation on Earth and is the primary greenhouse gas. Since evaporation increases with increasing sea surface temperature, and the increase in water vapor further increases greenhouse warming, there is a positive feedback. The runaway greenhouse effect occurs if this feedback continues unchecked until all the water has left the surface and enters the atmosphere. For Mars and the Earth the runaway greenhouse was halted when water vapor became saturated with respect to ice or liquid water respectively. However, Venus is considered to be an example of a planet where the runaway greenhouse effect did occur, and it has been speculated that if the solar luminosity were to increase above a certain limit, it would also occur on the Earth. Satellite data acquired during the Earth Radiation Budget Experiment (ERBE) under clear sky conditions shows that as the sea surface temperature (SST) increases, the rate of outgoing infrared radiation at the top of the atmosphere also increases, as expected. Over the pacific warm pool where the SST exceeds 300 K the outgoing radiation emitted to space actually decreases with increasing SST, leading to a potentially unstable system. This behavior is a signature of the runaway greenhouse effect on Earth. However, the SST never exceeds 303K, thus the system has a natural cap which stops the runaway. According to Stefan-Boltzmann's law the amount of heat energy radiated by the Earth's surface is proportional to (T(sup 4)). However, if the planet has a substantial atmosphere, it can absorb all infrared radiation from the lower surface before the radiation penetrates into outer space. Thus, an instrument in space looking at the planet does not detect radiation from the surface. The radiation it sees comes from some level higher up. For the earth#s atmosphere the effective temperature (T(sub e)) has a value of 255 K corresponding to the middle troposphere, above most of the

  20. Systematic Effects in Earth Orientation Parameters Determined by VLBI

    NASA Astrophysics Data System (ADS)

    Schuh, H.; Heinkelmann, R.

    2015-12-01

    Very Long Baseline Interferometry (VLBI) is the only technique that directly connects on the observation level the realizations of ITRS and ICRS in terms of their orientation. Many applications in spacecraft navigation, fundamental astronomy, astrometry and geosciences depend on the Earth Orientation Parameters (EOP) determined by VLBI. Currently, under the IAG/IAU Joint Working Group on the Theory of Earth Rotation, activities are supported to advance the theory of Earth rotation. Some components of Earth Rotation, such as the free modes like the Free Core Nutation (FCN) are not predictable but rely entirely on the observation through VLBI. In our presentation we investigate the EOP when alternating various VLBI analysis options such as correction models, a priori parameters, and other choices with the aim to detect and quantify possible systematic effects. Our approach is purely empirical: we alternate certain analysis options and assess the differences with respect to the reference solution that adheres to the IERS Conventions (2010) and applies the standard parameterization. For demonstration we analyze the regular International VLBI Service for Geodesy and Astrometry (IVS) sessions IVS-R1 and IVS-R4.The IAG flagship component GGOS (Global Geodetic Observing System) aims to provide the EOP with an accuracy of 1 mm on the Earth surface (about 30 microarcseconds). This accuracy target will be applied as a limit to interpret the significance of the differences obtained in our comparisons.

  1. A review of ionospheric effects on Earth-space propagation

    NASA Technical Reports Server (NTRS)

    Klobuchar, J. A.

    1984-01-01

    A short description is given of each ionospheric total electron content (TEC) effect upon radio waves, along with a representative value of the magnitude of each of these effects under normal ionospheric conditions. A discussion is given of the important characteristics of average ionospheric TEC behavior and the temporal and spatial variability of TEC. Radio waves undergo several effects when they pass through the Earth's ionosphere. One of the most important of these effects is a retardation, or group delay, on the modulation or information carried on the radio wave that is due to its encounter with the free, thermal electrons in the Earth's ionosphere. Other effects the ionosphere has on radio waves include: radio frequency (RF) carrier phase advance; Doppler shift of the RF carrier of the radio wave; Faraday rotation of the plane of polarization of linearly polarized waves; angular refraction or bending of the radio wave path as it travels through the ionosphere; and amplitude and phase scintillations.

  2. A review of ionospheric effects on Earth-space propagation

    NASA Technical Reports Server (NTRS)

    Klobuchar, J. A.

    1984-01-01

    A short description is given of each ionospheric total electron content (TEC) effect upon radio waves, along with a representative value of the magnitude of each of these effects under normal ionospheric conditions. A discussion is given of the important characteristics of average ionospheric TEC behavior and the temporal and spatial variability of TEC. Radio waves undergo several effects when they pass through the Earth's ionosphere. One of the most important of these effects is a retardation, or group delay, on the modulation or information carried on the radio wave that is due to its encounter with the free, thermal electrons in the Earth's ionosphere. Other effects the ionosphere has on radio waves include: radio frequency (RF) carrier phase advance; Doppler shift of the RF carrier of the radio wave; Faraday rotation of the plane of polarization of linearly polarized waves; angular refraction or bending of the radio wave path as it travels through the ionosphere; and amplitude and phase scintillations.

  3. Dynamic ocean-tide effects on Earth's rotation

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.

    1993-01-01

    This article develops 'broad-band' Liouville equations which are capable of determining the effects on the rotation of the Earth of a periodic excitation even at frequencies as high as semi-diurnal; these equations are then used to predict the rotational effects of altimetric, numerical and 32-constituent spherical harmonic ocean-tide models. The rotational model includes a frequency-dependent decoupled core, the effects of which are especially marked near retrograde diurnal frequencies; and a fully dynamic oceanic response, whose effects appear to be minor despite significant frequency dependence. The model also includes solid-earth effects which are frequency dependent as the result of both anelasticity at long periods and the fluid-core resonance at nearly diurnal periods. The effects of both tidal inertia and relative angular momentum on Earth rotation (polar motion, length of day, 'nutation' and Universal Time) are presented for 32 long- and short-period ocean tides determined as solutions to the author's spherical harmonic tide theory. The lengthening of the Chandler wobble period by the pole tide is also re-computed using the author's full theory. Additionally, using the spherical harmonic theory, tidal currents and their effects on rotation are determined for available numerical and altimetric tide height models. For all models, we find that the effects of tidal currents are at least as important as those of tide height for diurnal and semi-diurnal constituents.

  4. Dynamic ocean-tide effects on Earth's rotation

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.

    1993-01-01

    This article develops 'broad-band' Liouville equations which are capable of determining the effects on the rotation of the Earth of a periodic excitation even at frequencies as high as semi-diurnal; these equations are then used to predict the rotational effects of altimetric, numerical and 32-constituent spherical harmonic ocean-tide models. The rotational model includes a frequency-dependent decoupled core, the effects of which are especially marked near retrograde diurnal frequencies; and a fully dynamic oceanic response, whose effects appear to be minor despite significant frequency dependence. The model also includes solid-earth effects which are frequency dependent as the result of both anelasticity at long periods and the fluid-core resonance at nearly diurnal periods. The effects of both tidal inertia and relative angular momentum on Earth rotation (polar motion, length of day, 'nutation' and Universal Time) are presented for 32 long- and short-period ocean tides determined as solutions to the author's spherical harmonic tide theory. The lengthening of the Chandler wobble period by the pole tide is also re-computed using the author's full theory. Additionally, using the spherical harmonic theory, tidal currents and their effects on rotation are determined for available numerical and altimetric tide height models. For all models, we find that the effects of tidal currents are at least as important as those of tide height for diurnal and semi-diurnal constituents.

  5. A very sensitive high-resolution NMR method for quadrupolar nuclei: SPAM-DQF-STMAS.

    PubMed

    Amoureux, Jean-Paul; Flambard, Alexandrine; Delevoye, Laurent; Montagne, Lionel

    2005-07-21

    We show that by combining the intrinsically larger (with respect to MQMAS) efficiency of Double-Quantum Filtered Satellite-Transition MAS (DQF-STMAS), with the large S/N gain of the Soft-Pulse Added Mixing (SPAM) concept, a new very sensitive high-resolution solid-state NMR method can be obtained for semi-integer quadrupolar nuclei.

  6. The Effects of Earth Science Programs on Student Knowledge and Interest in Earth Science

    NASA Astrophysics Data System (ADS)

    Wilson, A.

    2016-12-01

    Ariana Wilson, Chris Skinner, Chris Poulsen Abstract For many years, academic programs have been in place for the instruction of young students in the earth sciences before they undergo formal training in high school or college. However, there has been little formal assessment of the impacts of these programs on student knowledge of the earth sciences and their interest in continuing with earth science. On August 6th-12th 2016 I will attend the University of Michigan's annual Earth Camp, where I will 1) ascertain high school students' knowledge of earth science-specifically atmospheric structure and wind patterns- before and after Earth Camp, 2) record their opinions about earth science before and after Earth Camp, and 3) record how the students feel about how the camp was run and what could be improved. I will accomplish these things through the use of surveys asking the students questions about these subjects. I expect my results will show that earth science programs like Earth Camp deepen students' knowledge of and interest in earth science and encourage them to continue their study of earth science in the future. I hope these results will give guidance on how to conduct future learning programs and how to recruit more students to become earth scientists in the future.

  7. Effects of megascale eruptions on Earth and Mars

    USGS Publications Warehouse

    Thordarson, T.; Rampino, M.; Keszthelyi, L.P.; Self, S.

    2009-01-01

    Volcanic features are common on geologically active earthlike planets. Megascale or "super" eruptions involving >1000 Gt of magma have occurred on both Earth and Mars in the geologically recent past, introducing prodigious volumes of ash and volcanic gases into the atmosphere. Here we discuss felsic (explosive) and mafi c (flood lava) supereruptions and their potential atmospheric and environmental effects on both planets. On Earth, felsic supereruptions recur on average about every 100-200,000 years and our present knowledge of the 73.5 ka Toba eruption implies that such events can have the potential to be catastrophic to human civilization. A future eruption of this type may require an unprecedented response from humankind to assure the continuation of civilization as we know it. Mafi c supereruptions have resulted in atmospheric injection of volcanic gases (especially SO2) and may have played a part in punctuating the history of life on Earth. The contrast between the more sustained effects of flood basalt eruptions (decades to centuries) and the near-instantaneous effects of large impacts (months to years) is worthy of more detailed study than has been completed to date. Products of mafi c supereruptions, signifi cantly larger than known from the geologic record on Earth, are well preserved on Mars. The volatile emissions from these eruptions most likely had global dispersal, but the effects may not have been outside what Mars endures even in the absence of volcanic eruptions. This is testament to the extreme variability of the current Martian atmosphere: situations that would be considered catastrophic on Earth are the norm on Mars. ?? 2009 The Geological Society of America.

  8. Proton detection of MAS solid-state NMR spectra of half-integer quadrupolar nuclei.

    PubMed

    Venkatesh, Amrit; Hanrahan, Michael P; Rossini, Aaron J

    Fast magic angle spinning (MAS) and proton detection has found widespread application to enhance the sensitivity of solid-state NMR experiments with spin-1/2 nuclei such as (13)C, (15)N and (29)Si, however, this approach is not yet routinely applied to half-integer quadrupolar nuclei. Here we have investigated the feasibility of using fast MAS and proton detection to enhance the sensitivity of solid-state NMR experiments with half-integer quadrupolar nuclei. The previously described dipolar hetero-nuclear multiple quantum correlation (D-HMQC) and dipolar refocused insensitive nuclei enhanced by polarization transfer (D-RINEPT) pulse sequences were used for proton detection of half-integer quadrupolar nuclei. Quantitative comparisons of signal-to-noise ratios and the sensitivity of proton detected D-HMQC and D-RINEPT and direct detection spin echo and quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) solid-state NMR spectra, demonstrate that one dimensional proton detected experiments can provide sensitivity similar to or exceeding that obtainable with direct detection QCPMG experiments. 2D D-HMQC and D-RINEPT experiments provide less sensitivity than QCPMG experiments but proton detected 2D hetero-nuclear correlation solid-state NMR spectra of half-integer nuclei can still be acquired in about the same time as a 1D spin echo spectrum. Notably, the rarely used D-RINEPT pulse sequence is found to provide similar, or better sensitivity than D-HMQC in some cases. Proton detected D-RINEPT benefits from the short longitudinal relaxation times (T1) normally associated with half-integer quadrupolar nuclei, it can be combined with existing signal enhancement methods for quadrupolar nuclei, and t1-noise in the indirect dimension can easily be removed by pre-saturation of the (1)H nuclei. The rapid acquisition of proton detected 2D HETCOR solid-state NMR spectra of a range of half-integer quadrupolar nuclei such as (17)O, (27)Al, (35)Cl and (71)Ga is demonstrated. Copyright

  9. Design of Scalable and Effective Earth Science Collaboration Tool

    NASA Astrophysics Data System (ADS)

    Maskey, M.; Ramachandran, R.; Kuo, K. S.; Lynnes, C.; Niamsuwan, N.; Chidambaram, C.

    2014-12-01

    Collaborative research is growing rapidly. Many tools including IDEs are now beginning to incorporate new collaborative features. Software engineering research has shown the effectiveness of collaborative programming and analysis. In particular, drastic reduction in software development time resulting in reduced cost has been highlighted. Recently, we have witnessed the rise of applications that allow users to share their content. Most of these applications scale such collaboration using cloud technologies. Earth science research needs to adopt collaboration technologies to reduce redundancy, cut cost, expand knowledgebase, and scale research experiments. To address these needs, we developed the Earth science collaboration workbench (CWB). CWB provides researchers with various collaboration features by augmenting their existing analysis tools to minimize learning curve. During the development of the CWB, we understood that Earth science collaboration tasks are varied and we concluded that it is not possible to design a tool that serves all collaboration purposes. We adopted a mix of synchronous and asynchronous sharing methods that can be used to perform collaboration across time and location dimensions. We have used cloud technology for scaling the collaboration. Cloud has been highly utilized and valuable tool for Earth science researchers. Among other usages, cloud is used for sharing research results, Earth science data, and virtual machine images; allowing CWB to create and maintain research environments and networks to enhance collaboration between researchers. Furthermore, collaborative versioning tool, Git, is integrated into CWB for versioning of science artifacts. In this paper, we present our experience in designing and implementing the CWB. We will also discuss the integration of collaborative code development use cases for data search and discovery using NASA DAAC and simulation of satellite observations using NASA Earth Observing System Simulation

  10. Effects of Long Period Ocean Tides on the Earth's Rotation

    NASA Technical Reports Server (NTRS)

    Gross, Richard S.; Chao, Ben F.; Desai, Shailen D.

    1996-01-01

    The spectra of polar motion excitation functions exhibit enhanced power in the fortnightly tidal band. This enhanced power is attributed to ocean tidal excitation. Ocean tide models predict polar motion excitation effects that differ with each other, and with observations, by factors as large as 2-3. There is a need for inproved models for the effect of long-period ocean tides on Earth's rotation.

  11. Earth Impact Effects Program: Estimating the Regional Environmental Consequences of Impacts On Earth

    NASA Astrophysics Data System (ADS)

    Collins, G. S.; Melosh, H. J.; Marcus, R. A.

    2009-12-01

    The Earth Impact Effects Program (www.lpl.arizona.edu/impacteffects) is a popular web-based calculator for estimating the regional environmental consequences of a comet or asteroid impact on Earth. It is widely used, both by inquisitive members of the public as an educational device and by scientists as a simple research tool. It applies a variety of scaling laws, based on theory, nuclear explosion test data, observations from terrestrial and extraterrestrial craters and the results of small-scale impact experiments and numerical modelling, to quantify the principal hazards that might affect the people, buildings and landscape in the vicinity of an impact. The program requires six inputs: impactor diameter, impactor density, impact velocity prior to atmospheric entry, impact angle, and the target type (sedimentary rock, crystalline rock, or a water layer above rock), as well as the distance from the impact at which the environmental effects are to be calculated. The program includes simple algorithms for estimating the fate of the impactor during atmospheric traverse, the thermal radiation emitted by the impact plume (fireball) and the intensity of seismic shaking. The program also approximates various dimensions of the impact crater and ejecta deposit, as well as estimating the severity of the air blast in both crater-forming and airburst impacts. We illustrate the strengths and limitations of the program by comparing its predictions (where possible) against known impacts, such as Carancas, Peru (2007); Tunguska, Siberia (1908); Barringer (Meteor) crater, Arizona (ca 49 ka). These tests demonstrate that, while adequate for large impactors, the simple approximation of atmospheric entry in the original program does not properly account for the disruption and dispersal of small impactors as they traverse Earth's atmosphere. We describe recent improvements to the calculator to better describe atmospheric entry of small meteors; the consequences of oceanic impacts; and

  12. Semi-empirical refinements of crystal structures using (17)O quadrupolar-coupling tensors.

    PubMed

    Holmes, Sean T; Iuliucci, Robbie J; Mueller, Karl T; Dybowski, Cecil

    2017-02-14

    We demonstrate a modification of Grimme's two-parameter empirical dispersion force field (referred to as the PW91-D2* method), in which the damping function has been optimized to yield geometries that result in predictions of the principal values of (17)O quadrupolar-coupling tensors that are systematically in close agreement with experiment. The predictions of (17)O quadrupolar-coupling tensors using PW91-D2*-refined structures yield a root-mean-square deviation (RMSD) (0.28 MHz) for twenty-two crystalline systems that is smaller than the RMSD for predictions based on X-ray diffraction structures (0.58 MHz) or on structures refined with PW91 (0.53 MHz). In addition, (13)C, (15)N, and (17)O chemical-shift tensors and (35)Cl quadrupolar-coupling tensors determined with PW91-D2*-refined structures are compared to the experiment. Errors in the prediction of chemical-shift tensors and quadrupolar-coupling tensors are, in these cases, substantially lowered, as compared to predictions based on PW91-refined structures. With this PW91-D2*-based method, analysis of 42 (17)O chemical-shift-tensor principal components gives a RMSD of only 18.3 ppm, whereas calculations on unrefined X-ray structures give a RMSD of 39.6 ppm and calculations of PW91-refined structures give an RMSD of 24.3 ppm. A similar analysis of (35)Cl quadrupolar-coupling tensor principal components gives a RMSD of 1.45 MHz for the unrefined X-ray structures, 1.62 MHz for PW91-refined structures, and 0.59 MHz for the PW91-D2*-refined structures.

  13. The effects of the solid inner core and nonhydrostatic structure on the earth's forced nutations and earth tides

    NASA Technical Reports Server (NTRS)

    De Vries, Dan; Wahr, John M.

    1991-01-01

    This paper computes the effects of the solid inner core (IC) on the forced nutations and earth tides, and on certain of the earth's rotational normal modes. The theoretical results are extended to include the effects of a solid IC and of nonhydrostatic structure. The presence of the IC is responsible for a new, almost diurnal, prograde normal mode which involves a relative rotation between the IC and fluid outer core about an equatorial axis. It is shown that the small size of the IC's effects on both nutations and tides is a consequence of the fact that the IC's moments of inertia are less than 1/1000 of the entire earth's.

  14. The effects of the solid inner core and nonhydrostatic structure on the earth's forced nutations and earth tides

    NASA Technical Reports Server (NTRS)

    De Vries, Dan; Wahr, John M.

    1991-01-01

    This paper computes the effects of the solid inner core (IC) on the forced nutations and earth tides, and on certain of the earth's rotational normal modes. The theoretical results are extended to include the effects of a solid IC and of nonhydrostatic structure. The presence of the IC is responsible for a new, almost diurnal, prograde normal mode which involves a relative rotation between the IC and fluid outer core about an equatorial axis. It is shown that the small size of the IC's effects on both nutations and tides is a consequence of the fact that the IC's moments of inertia are less than 1/1000 of the entire earth's.

  15. Spin-locking of half-integer quadrupolar nuclei in NMR of solids: The far off-resonance case.

    PubMed

    Odedra, Smita; Wimperis, Stephen

    Spin-locking of spin I=3/2 and I=5/2 nuclei in the presence of large resonance offsets has been studied using both approximate and exact theoretical approaches and, in the case of I=3/2, experimentally. We show the variety of coherences and population states produced in a far off-resonance spin-locking NMR experiment (one consisting solely of a spin-locking pulse) and how these vary with the radiofrequency field strength and offset frequency. Under magic angle spinning (MAS) conditions and in the "adiabatic limit", these spin-locked states acquire a time dependence. We discuss the rotor-driven interconversion of the spin-locked states, using an exact density matrix approach to confirm the results of the approximate model. Using conventional and multiple-quantum filtered spin-locking (23)Na (I=3/2) NMR experiments under both static and MAS conditions, we confirm the results of the theoretical calculations, demonstrating the applicability of the approximate theoretical model to the far off-resonance case. This simplified model includes only the effects of the initial rapid dephasing of coherences that occurs at the start of the spin-locking period and its success in reproducing both experimental and exact simulation data indicates that it is this dephasing that is the dominant phenomenon in NMR spin-locking of quadrupolar nuclei, as we have previously found for the on-resonance and near-resonance cases. Potentially, far off-resonance spin-locking of quadrupolar nuclei could be of interest in experiments such as cross polarisation as a consequence of the spin-locking pulse being applied to a better defined initial state (the thermal equilibrium bulk magnetisation aligned along the z-axis) than can be created in a powdered solid with a selective radiofrequency pulse, where the effect of the pulse depends on the orientation of the individual crystallites. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Magnetostatic Effects in the Nucleation of Rare Earth Ferromagnetic Phases

    SciTech Connect

    Durfee, C. S.; Flynn, C. P.

    2001-07-30

    It has been reported that superheating, supercooling, and explosive kinetics coupled to other degrees of freedom occur at the ferromagnetic transitions of Er and Dy, and that metastable phases occur during the transition kinetics of Er. We explain these observations in terms of magnetostatic energy, which requires highly eccentric nuclei in the homogeneous nucleation of magnetic transitions in heavy rare earths. The magnetostatics favor transitions through ferrimagnetic intermediaries. The unusual kinetics derive from effective spin lattice relaxation.

  17. Earth matter effect on active-sterile neutrino oscillations

    NASA Astrophysics Data System (ADS)

    Acero, Mario A.; Aguilar-Arevalo, Alexis A.; D'Olivo, J. C.

    2011-08-01

    Oscillations between active and sterile neutrinos remain as an open possibility to explain some experimental observations. In a four-neutrino mixing scheme, we use the Magnus expansion of the evolution operator to study the evolution of neutrino flavor amplitudes within the Earth. We apply this formalism to calculate the transition probabilities from active to sterile neutrinos taking into account the matter effect for a varying terrestrial density.

  18. On the tidal effects in the motion of earth satellites and the love parameters of the earth

    NASA Technical Reports Server (NTRS)

    Musen, P.; Estes, R.

    1972-01-01

    The tidal effects in the motion of artificial satellites are studied to determine the elastic properties of the earth as they are observed from extraterrestrial space. Considering Love numbers, the disturbing potential is obtained as the analytical continuation of the tidal potential from the surface of the earth into-outer space, with parameters which characterize the earth's elastic response to tidal attraction by the moon and the sun. It is concluded that the tidal effects represent a superposition of a large number of periodic terms, and the rotation of the lunar orbital plane produces a term of 18 years period in tidal perturbations of the ascending node of the satellite's orbit.

  19. Three-Dimensional Orbits of Earth Satellites, Including Effects of Earth Oblateness and Atmospheric Rotation

    NASA Technical Reports Server (NTRS)

    Nielsen, Jack N.; Goodwin, Frederick K.; Mersman, William A.

    1958-01-01

    The principal purpose of the present paper is to present sets of equations which may be used for calculating complete trajectories of earth satellites from outer space to the ground under the influence of air drag and gravity, including oblateness effects, and to apply these to several examples of entry trajectories starting from a circular orbit. Equations of motion, based on an "instantaneous ellipse" technique, with polar angle as independent variable, were found suitable for automatic computation of orbits in which the trajectory consists of a number of revolutions. This method is suitable as long as the trajectory does not become nearly vertical. In the terminal phase of the trajectories, which are nearly vertical, equations of motion in spherical polar coordinates with time as the independent variable were found to be more suitable. In the first illustrative example the effects of the oblateness component of the earth's gravitational field and of atmospheric rotation were studied for equatorial orbits. The satellites were launched into circular orbits at a height of 120 miles, an altitude sufficiently high that a number of revolutions could be studied. The importance of the oblateness component of the earth's gravitational field is shown by the fact that a satellite launched at circular orbital speed, neglecting oblateness, has a perigee some 67,000 feet lower when oblateness forces are included in the equations of motion than when they are not included. Also, the loss in altitude per revolution is double that of a satellite following an orbit not subject to oblateness. The effect of atmospheric rotation on the loss of altitude per revolution was small. As might be surmised, the regression of the line of nodes as predicted by celestial mechanics is unchanged when drag is included. It is clear that the inclination of the orbital plane to the equator will be relatively unaffected by drag for no atmospheric rotation since the drag lies in the orbital plane in

  20. Investigating Earth shadowing effect with DAMA/LIBRA-phase1

    NASA Astrophysics Data System (ADS)

    Bernabei, R.; Belli, P.; d'Angelo, S.; Di Marco, A.; Montecchia, F.; d'Angelo, A.; Incicchitti, A.; Cappella, F.; Caracciolo, V.; Cerulli, R.; Dai, C. J.; He, H. L.; Kuang, H. H.; Ma, X. H.; Sheng, X. D.; Wang, R. G.; Ye, Z. P.

    2015-05-01

    In the present paper the results obtained in the investigation of possible diurnal effects for low-energy single-hit scintillation events of DAMA/LIBRA-phase1 (1.04 ton year exposure) have been analysed in terms of an effect expected in case of dark matter (DM) candidates inducing nuclear recoils and having high cross-section with ordinary matter, which implies low DM local density in order to fulfill the DAMA/LIBRA DM annual modulation results. This effect is due to the different Earth depths crossed by those DM candidates during the sidereal day.

  1. Anomalous Hall Effect in a Feromagnetic Rare-Earth Cobalite

    NASA Technical Reports Server (NTRS)

    Samoilov, A. V.; Yeh, N. C.; Vasquez, R. P.

    1996-01-01

    Rare-Earth manganites and cobalites with the perovskite structure have been a subject of great recent interest because their electrical resistance changes significantly when a magnetic field is applied...we have studied the Hall effect in thin film La(sub 0.5)Ca(sub 0.5)CoO(sub 3) material and have obtained convincing evidence fo the so called anomalous Hall effect, typical for magnetic metals...Our results suggest that near the ferromagnetic ordering temperature, the dominant electron scattering mechanism is the spin fluctuation.

  2. Atmospheric effects on earth rotation and polar motion

    NASA Technical Reports Server (NTRS)

    Salstein, David A.

    1988-01-01

    The variability in the earth's rotation rate not due to known solid body tides is dominated on time scales of about four years and less by variations in global atmospheric angular momentum (M) as derived from the zonal wind distribution. Among features seen in the length of day record produced by atmospheric forcing are the strong seasonal cycle, quasi-periodic fluctuations around 40-50 days, and an interannual signal forced by a strong Pacific warming event known as the El Nino. Momentum variations associated with these time scales arise in different latitudinal regions. Furthermore, winds in the stratosphere make a particularly important contribution to seasonal variability. Other related topics discussed here are: (1) comparisons of the M series from wind fields produced at different weather centers; (2) the torques that dynamically link the atmosphere and earth; and (3) longer-term nonatmospheric effects that can be seen upon removal of the atmospheric signal.an interestigapplication for climatological purposes is the use of the historical earth rotation series as a proxy for atmospheric wind variability prior to the era of upper-air data. Lastly, results pertaining to the role of atmospheric pressure systems in exciting rapid polar motion are presented.

  3. Atmospheric effects on earth rotation and polar motion

    NASA Technical Reports Server (NTRS)

    Salstein, David A.

    1988-01-01

    The variability in the earth's rotation rate not due to known solid body tides is dominated on time scales of about four years and less by variations in global atmospheric angular momentum (M) as derived from the zonal wind distribution. Among features seen in the length of day record produced by atmospheric forcing are the strong seasonal cycle, quasi-periodic fluctuations around 40-50 days, and an interannual signal forced by a strong Pacific warming event known as the El Nino. Momentum variations associated with these time scales arise in different latitudinal regions. Furthermore, winds in the stratosphere make a particularly important contribution to seasonal variability. Other related topics discussed here are: (1) comparisons of the M series from wind fields produced at different weather centers; (2) the torques that dynamically link the atmosphere and earth; and (3) longer-term nonatmospheric effects that can be seen upon removal of the atmospheric signal.an interestigapplication for climatological purposes is the use of the historical earth rotation series as a proxy for atmospheric wind variability prior to the era of upper-air data. Lastly, results pertaining to the role of atmospheric pressure systems in exciting rapid polar motion are presented.

  4. Effect of rare earth oxides for improvement of MCFC

    NASA Astrophysics Data System (ADS)

    Ota, Ken-ichiro; Matsuda, Yoshiyuki; Matsuzawa, Koichi; Mitsushima, Shigenori; Kamiya, Nobuyuki

    The solubility of rare earth metal oxides and their effect on the NiO solubility have been discussed to stabilize the cathode of molten carbonate fuel cells. The solubility of Ho, Yb, and Nd oxides were 4.4 × 10 -4, 3.4 × 10 -4, and 1.3 × 10 -3 (mole fraction) at 923 K, respectively. The solubilities of NiO in (Li 0.52/Na 0.48) 2CO 3 with the saturated Ho, Yb, and Nd were 1.57 × 10 -5, 1.41 × 10 -5, and 9.5 × 10 -6, respectively. Among these three, Nd, which has the highest solubility in the carbonates, reduced the NiO solubility most; although, the La reduced the NiO solubility more than Nd. The logarithm of the solubility of the rare earth metal oxides has a linear relation to the Coulomb force ratio between the rare earth metal and the alkaline metal. Following this relation, the La should have the highest solubility among all the lanthanides. The basicity which NiO solubility closely relates has a linear relationship to the Coulomb force parameter of the melts. Based on these two models, the La would be the best additive to reduce the NiO solubility in Li/Na eutectic carbonate melt, among all the lanthanides.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

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

    PubMed

    Karakatsani, Eirini K; Economou, Ioannis G

    2006-05-11

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  8. H_2 bipolar emission associated with the quadrupolar molecular outflow in L723

    NASA Astrophysics Data System (ADS)

    Palacios, Javier; Eiroa, Carlos

    1999-06-01

    We present near-infrared images of the quadrupolar CO outflow in L723, formed by two lobe pairs of different size. Bipolar molecular hydrogen line emission is detected, approximately centered on the Class 0 source L723 VLA2. One of the observed H_2 nebulosities coincides with the Herbig-Haro object HH 223. The H_2 bipolar outflow is projected against the large lobe pair of the quadrupolar CO outflow. Position angles of the H_2 and HH emissions, large CO lobe pair and the thermal radio jet VLA2 are similar and also close to the magnetic field direction in the region. All these phenomena are likely powered by the young protostellar object L723 VLA2. Our near-infrared images do not show any near-ir counterpart of the smaller CO pair, whose origin and driving source remain unclear.

  9. Quadrupolar ordering in LaMnO3 revealed from scattering data and geometric modeling.

    PubMed

    Sartbaeva, A; Wells, S A; Thorpe, M F; Bozin, E S; Billinge, S J L

    2007-10-12

    Many strongly correlated materials display quadrupolar (Jahn-Teller) distortion of the local octahedral structural units. It is common for these distortions to be observed by probes of local structure but absent in the crystallographic average structure. The ordering of these quadrupoles is important in determining the properties of manganites and cuprates, and the nature of the disorder in these structures has been an unsolved problem. We combine high resolution scattering data and novel geometrical modeling techniques to obtain a detailed picture of the local atomic structure, and also to extract the quadrupolar order parameter associated with the distorted octahedra. We show that in LaMnO3, quadrupoles undergo a strong first-order phase transition at 730 K, but with nonzero order parameter remaining in the high-temperature phase.

  10. Population difference thermometry: quadrupolar splitting of NMR lines of MnSb

    NASA Astrophysics Data System (ADS)

    Andersen, P. M.; Sullivan, N. S.; Andraka, B.; Xia, J. S.; Adams, E. D.

    1992-12-01

    We report the results of a study to use the intensity ratios of the multiplet spectra of the quadrupolar-perturbed ferromagnetic resonance absorption in MnSb as a reliable first principles, self-calibrating, ultra-low temperature thermometer. The method proposed is very general and is applicable to a variety of magnetic resonances with multiplet spectra for which the intensities of the absorption depend on the thermal population of the nuclear Zeeman levels.

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

    PubMed

    Warshavsky, V B; Zeng, X C

    2013-10-07

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  13. The effect of atmospheric pressure on Snowball Earth deglaciation

    NASA Astrophysics Data System (ADS)

    Edkins, Nicholas; Davies, Roger

    2017-02-01

    The most common explanation for the escape from a Snowball Earth state involves, among other factors, a strong greenhouse effect caused by a large partial pressure of CO2. This leads to an increase in surface pressure, which most models do not account for. With a higher surface pressure, pressure broadening increases, and convection reaches a deeper layer, both of which result in higher surface temperatures. The latter mechanism, which has not previously been reported, is found to be a greater source of warming than pressure broadening in the normal range of CO2 partial pressures at the point of deglaciation.

  14. The Effect of Dust on Snowball Earth Climate

    NASA Astrophysics Data System (ADS)

    Li, D.; Pierrehumbert, R.

    2013-12-01

    The Neoproterozoic Era was marked by several episodes of global-scale glaciations termed as "Snowball Earth", when most of the Earth surface was blanketed by thick ice covers. Silicate weathering being suppressed, steady build-up of atmospheric CO2 is believed to be responsible for the deglaciation of snowball earths. However, GCM simulations suggest the radiative forcing from CO2 alone might be insufficient for deglaciation, and dust has been proposed as an auxiliary factor. Here we endeavor to build a comprehensive view on the unique role of dust in a snowball climate system. Based on an axisymmetric flow model of the marine ice cover, we show that in the tropical region, dust can accumulate on ice surface, forming a dusty band encircling the Earth. The feedback of dust to the snowball climate is investigated using a GCM coupled to the ice-dust model. In the scenario of weak aeolian transport, the dust layer atop suppresses the sublimation of ice. Water vapor diffuses through the pores of the dust layer, which is analogous to the process on present-day Mars. With the coupled model, we demonstrate the interplay between cloud and surface dust, and the associated change of global precipitation pattern. In another scenario where strong aeolian transport is present, dust is recycled back to the atmosphere after being exposed at the surface. As revealed in the axisymmetric ice model, the flowing ice cover effectively seals the ocean from becoming a sink for dust, then dust accumulates and darkens the ice during the lifetime of a snowball event. In both scenarios, the low albedo of surface dust increases the absorption of solar radiation and warms the climate. In further simulations we use a more sophisticated 3-D hybrid ice sheet-sea glacier model to study the transport of dust by the ice flow, and estimate the portion of dust being deposited into the ocean. This could serve as a theoretical basis for testing potential candidates of snowball earth with ocean floor

  15. Magnus Effect on a Spinning Satellite in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Ramjatan, Sahadeo; Fitz-Coy, Norman; Yew, Alvin Garwai

    2016-01-01

    A spinning body in a flow field generates an aerodynamic lift or Magnus effect that displaces the body in a direction normal to the freestream flow. Earth orbiting satellites with substantial body rotation in appreciable atmospheric densities may generate a Magnus force to perturb orbital dynamics. We investigate the feasibility of using this effect for spacecraft at a perigee of 80km using the Systems Tool Kit (STK). Results show that for a satellite of reasonable properties, the Magnus effect doubles the amount of time in orbit. Orbital decay was greatly mitigated for satellites spinning at 10000 and 15000RPM. This study demonstrates that the Magnus effect has the potential to sustain a spacecraft's orbit at a low perigee altitude and could also serve as an orbital maneuver capability.

  16. The thermodynamic effect of atmospheric mass on early Earth's temperature

    NASA Astrophysics Data System (ADS)

    Chemke, R.; Kaspi, Y.; Halevy, I.

    2016-11-01

    Observations suggest that Earth's early atmospheric mass differed from the present day. The effects of a different atmospheric mass on radiative forcing have been investigated in climate models of variable sophistication, but a mechanistic understanding of the thermodynamic component of the effect of atmospheric mass on early climate is missing. Using a 3-D idealized global circulation model (GCM), we systematically examine the thermodynamic effect of atmospheric mass on near-surface temperature. We find that higher atmospheric mass tends to increase the near-surface temperature mostly due to an increase in the heat capacity of the atmosphere, which decreases the net radiative cooling effect in the lower layers of the atmosphere. Additionally, the vertical advection of heat by eddies decreases with increasing atmospheric mass, resulting in further near-surface warming. As both net radiative cooling and vertical eddy heat fluxes are extratropical phenomena, higher atmospheric mass tends to flatten the meridional temperature gradient.

  17. The radiative effect of aerosols in the earth's atmosphere

    NASA Technical Reports Server (NTRS)

    Wang, W.-C.; Domoto, G. A.

    1974-01-01

    A modified two-flux approximation is employed to compute the transfer of radiation in a finite, inhomogeneous, turbid atmosphere. A perturbation technique is developed to allow the treatment of nongray gaseous absorption with multiple scattering. The perturbation method, which employs a backscatter factor as a parameter, can be used with anisotropic particle scattering as well as Rayleigh scattering. This method is used to study the effect of aerosols on radiative solar heating and infrared cooling as well as the radiative-convective temperature distribution in the earth's atmosphere. It is found that the effect of aerosols in the infrared cannot be neglected; while in the visible, the effect can be of the same order as that due to absorption by water vapor. For a high surface albedo (greater than 0.30) heating of the earth-atmosphere system results due to the presence of aerosols. The aerosols also reduce the amount of convection needed to maintain a stable atmosphere. For the case of a dense haze a temperature inversion is found to exist close to the ground.

  18. The Effect of Dark Matter on Solar System and Perihelion Precession of Earth Planet

    NASA Astrophysics Data System (ADS)

    Saadat, Hassan; Mousavi, S. N.; Saadat, M.; Saadat, N.; Saadat, A. M.

    2010-10-01

    This paper visualizes effect of dark matter on solar system and especially perihelion precession of Earth planet. The relation between the rate of perihelion shift of Earth planet and dark matter are obtained.

  19. WIMP capture and annihilation in the Earth in effective theories

    NASA Astrophysics Data System (ADS)

    Catena, Riccardo

    2017-01-01

    I calculate the rate of WIMP capture and annihilation in the Earth in the non-relativistic effective theory of dark matter-nucleon interactions. Neglecting operator interference, I consider all Galilean invariant interaction operators that can arise from the exchange of a heavy particle of spin less than or equal to one when WIMPs have spin 0, 1/2 or 1. I compute position and shape of the expected resonances in the mass—capture rate plane and show that Iron is not the most important element in the capture process for many currently ignored interaction operators. I compare these predictions with the recent results of an Earth WIMP analysis of IceCube in the 86-string configuration and set limits on all isoscalar and isovector coupling constants of the effective theory of dark matter-nucleon interactions. For certain interaction operators and for a dark matter particle mass of about 50 GeV, I find that these limits are stronger than those I have previously derived in an analysis of the solar WIMP search performed at IceCube in the 79-string configuration.

  20. The Effect of Cloud Type on Earth's Energy Imbalance

    NASA Astrophysics Data System (ADS)

    Hang, Y. A.; L'Ecuyer, T.

    2016-12-01

    Clouds have long been recognized as one of the largest uncertainties to predicting the evolution of Earth's changing energy imbalance. Previous research indicates that improved assessment of cloud impacts on climate requires a better understanding of distinct cloud types and their radiative effects. This work documents the effects of nine cloud types, distinguished based on their signatures in spaceborne active observations, on atmospheric radiative balance and heating using CloudSat's multi-sensor radiative fluxes and heating rates product. This dataset leverages high-resolution vertical cloud and aerosol information from CloudSat and CALIPSO to provide the most accurate estimates of vertically-resolved radiative fluxes available to date. The effects of three common cloud classes: cirrus, stratocumulus, and deep convection will be highlighted in detail to contrast their dramatically different effects on climate. The findings support the qualitative conclusion that cirrus clouds warm the planet and stratocumulus clouds cool the planet, while the longwave and shortwave cloud radiative effect of deep convective cloud largely cancel in the tropics. When all cloud types are considered, the estimated global annual mean shortwave forcing is in good agreement with previous estimates based on passive sensors but the CloudSat/CALIPSO observations suggest a lower longwave forcing than other sources. It will be further demonstrated that the cloud boundary information from the active sensors used provides improved capability to accurately discern the radiative effects of different cloud types at the Earth's surface, a critical factor in modulating the disposition of excess energy in the climate system.

  1. Fate of Earth Microbes on Mars -- UV Radiation Effects

    NASA Technical Reports Server (NTRS)

    Cockell, Charles

    2000-01-01

    A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment. Biological action spectra for DNA inactivation are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Although the present-day martian UV flux is similar to early earth and thus may not be a limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Here calculations for loss of microbial viability on the Pathfinder and Polar lander spacecraft are presented and the effects of martian dust on loss of viability are discussed. Details of the radiative transfer model are presented.

  2. Fate of Earth Microbes on Mars: UV Radiation Effects

    NASA Technical Reports Server (NTRS)

    Cockell, Charles

    2000-01-01

    A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment. Biological action spectra for DNA inactivation are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Although the present-day martian UV flux is similar to early earth and thus may not be a limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Here calculations for loss of microbial viability on the Pathfinder and Polar lander spacecraft are presented and the effects of martian dust on loss of viability are discussed. Details of the radiative transfer model are presented.

  3. Atomic oxygen effects on POSS polyimides in low earth orbit.

    PubMed

    Minton, Timothy K; Wright, Michael E; Tomczak, Sandra J; Marquez, Sara A; Shen, Linhan; Brunsvold, Amy L; Cooper, Russell; Zhang, Jianming; Vij, Vandana; Guenthner, Andrew J; Petteys, Brian J

    2012-02-01

    Kapton polyimde is extensively used in solar arrays, spacecraft thermal blankets, and space inflatable structures. Upon exposure to atomic oxygen in low Earth orbit (LEO), Kapton is severely eroded. An effective approach to prevent this erosion is to incorporate polyhedral oligomeric silsesquioxane (POSS) into the polyimide matrix by copolymerizing POSS monomers with the polyimide precursor. The copolymerization of POSS provides Si and O in the polymer matrix on the nano level. During exposure of POSS polyimide to atomic oxygen, organic material is degraded, and a silica passivation layer is formed. This silica layer protects the underlying polymer from further degradation. Laboratory and space-flight experiments have shown that POSS polyimides are highly resistant to atomic-oxygen attack, with erosion yields that may be as little as 1% those of Kapton. The results of all the studies indicate that POSS polyimide would be a space-survivable replacement for Kapton on spacecraft that operate in the LEO environment.

  4. Adiabatic sweep cross-polarization magic-angle-spinning NMR of half-integer quadrupolar spins

    NASA Astrophysics Data System (ADS)

    Wi, Sungsool; Kim, Chul; Schurko, Robert; Frydman, Lucio

    2017-04-01

    The use of frequency-swept radiofrequency (rf) pulses for enhancing signals in the magic-angle spinning (MAS) spectra of half-integer quadrupolar nuclides was explored. The broadband adiabatic inversion cross-polarization magic-angle spinning (BRAIN-CPMAS) method, involving an adiabatic inversion pulse on the S-channel and a simultaneous rectangular spin-lock pulse on the I-channel (1H), was applied to I(1/2) → S(3/2) systems. Optimal BRAIN-CPMAS matching conditions were found to involve low rf pulse strengths for both the I- and S-spin channels. At these low and easily attainable rf field strengths, level-crossing events among the energy levels | 3 / 2 >, | 1 / 2 >, | - 1 / 2 >, | - 3 / 2 > that are known to complicate the CPMAS of quadrupolar nuclei, are mostly avoided. Zero- and double-quantum polarization transfer modes, akin to those we have observed for I(1/2) → S(1/2) polarization transfers, were evidenced by these analyses even in the presence of the quadrupolar interaction. 1H-23Na and 1H-11B BRAIN-CPMAS conditions were experimentally explored on model compounds by optimizing the width of the adiabatic sweep, as well as the rf pulse powers of the 1H and 23Na/11B channels, for different MAS rates. The experimental data obtained on model compounds containing spin-3/2 nuclides, matched well predictions from numerical simulations and from an average Hamiltonian theory model. Extensions to half-integer spin nuclides with higher spins and potential applications of this BRAIN-CPMAS approach are discussed.

  5. Lunar effects on close encounters of hungaria asteroids and near-Earth asteroids with the Earth

    NASA Astrophysics Data System (ADS)

    Bazso, A.; Galiazzo, M.

    2012-12-01

    The Earth is target to many celestial objects, among them Near Earth Asteroids (NEA) play a significant role. Different dynamical groups have been found, the source of these asteroids is mainly the main belt and, in particular the Hungaria group. We carry out a statistical investigation by numerical integration of the motion of real asteroids and their hypothetical clones in a simplified dynamical model of the solar system up to 100 My. In a first part we present integrations of existing Hungaria asteroids to determine which of them could become NEAs. Then the influence of the Moon on the orbits of these NEAs is investigated. The main goal is to find the frequency of close encounters and deflection angles due to them, possible impacts and the strength of deflection by the Moon.

  6. Excited-state symmetry breaking of linear quadrupolar chromophores: A transient absorption study

    NASA Astrophysics Data System (ADS)

    Dozova, Nadia; Ventelon, Lionel; Clermont, Guillaume; Blanchard-Desce, Mireille; Plaza, Pascal

    2016-11-01

    The photophysical properties of two highly symmetrical quadrupolar chromophores were studied by both steady-state and transient absorption spectroscopy. Their excited-state behavior is dominated by the solvent-induced Stokes shift of the stimulated-emission band. The origin of this shift is attributed to symmetry breaking that confers a non-vanishing dipole moment to the excited state of both compounds. This dipole moment is large and constant in DMSO, whereas symmetry breaking appears significantly slower and leading to smaller excited-state dipole in toluene. Time-dependant increase of the excited-state dipole moment induced by weak solvation is proposed to explain the results in toluene.

  7. Quadrupolar benzobisthiazole-cored arylamines as highly efficient two-photon absorbing fluorophores.

    PubMed

    Hrobárik, Peter; Hrobáriková, Veronika; Semak, Vladislav; Kasák, Peter; Rakovský, Erik; Polyzos, Ioannis; Fakis, Mihalis; Persephonis, Peter

    2014-12-19

    A computer-aided design of novel D-π-A-π-D styrylamines containing five isomeric benzobisthiazole moieties as the electron-accepting core has revealed the linear centrosymmetric benzo[1,2-d:4,5-d']bisthiazole as the most promising building block for engineering chromophores displaying high two-photon absorption (TPA) in the near-IR region, as also confirmed experimentally. The ease of synthesis of quadrupolar derivatives thereof, combined with extraordinarly high TPA action cross sections (δTPAΦf > 1500 GM), makes these heteroaromatic systems particularly attractive as diagnostic agents in 3D fluorescence imaging.

  8. Pulsed field gradient multiple-quantum MAS NMR spectroscopy of half-integer spin quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Fyfe, C. A.; Skibsted, J.; Grondey, H.; Meyer zu Altenschildesche, H.

    1997-12-01

    Pulsed field gradients (PFGs) have been applied to select coherence transfer pathways in multiple-quantum (MQ) MAS NMR spectra of half-integer spin quadrupolar nuclei in rigid solids. 27Al triple-quantum (3Q) MAS NMR spectra of the aluminophosphate molecular sieves VPI-5 and AlPO 4-18 have been used to demonstrate the selection of the (0)→(3)→(-1) coherence transfer pathway using PFGs and no phase cycling. Compared to MQMAS experiments that employ phase cycling schemes, the main advantage of the PFG-MQMAS technique is its simplicity, which should facilitate the combination of MQMAS with other pulse sequences.

  9. Coexistence of the dipolar and quadrupolar orderings in SmTl 3

    NASA Astrophysics Data System (ADS)

    Liu, B.; Li, J. L.; Kasaya, M.; Kido, G.; Nakagawa, Y.; Kasuya, T.

    1990-12-01

    The temperature dependence of magnetization and high field magnetization up to 270 kOe for three principal directions were performed on the single crystal of the AuCu 3-type SmTl 3. It was found that SmTl 3 is ferromagnet with Tc = 5.8 K. The origin of anomaly reported at 8.6 K in the specific heat measurement seems to be due to the quadrupolar ordering because of its gG{8} ground state.

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

    SciTech Connect

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

    2015-03-15

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

  11. Effects of Rare Earth Metals on Steel Microstructures.

    PubMed

    Pan, Fei; Zhang, Jian; Chen, Hao-Long; Su, Yen-Hsun; Kuo, Chia-Liang; Su, Yen-Hao; Chen, Shin-Hau; Lin, Kuan-Ju; Hsieh, Ping-Hung; Hwang, Weng-Sing

    2016-05-27

    Rare earth metals are used in semiconductors, solar cells and catalysts. This review focuses on the background of oxide metallurgy technologies, the chemical and physical properties of rare earth (RE) metals, the background of oxide metallurgy, the functions of RE metals in steelmaking, and the influences of RE metals on steel microstructures. Future prospects for RE metal applications in steelmaking are also presented.

  12. 5f delocalization-induced suppression of quadrupolar order in U(Pd1-xPtx)₃

    DOE PAGES

    Walker, H. C.; Le, M. D.; McEwen, K. A.; ...

    2011-12-27

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

  13. Laboratory simulation of Low Earth Orbit (LEO) atomic oxygen effects

    NASA Technical Reports Server (NTRS)

    Caledonia, George E.; Krech, Robert H.; Oakes, David B.

    1994-01-01

    A pulsed fast oxygen atom source has been used extensively over the last 7 years to investigate the effects of ambient oxygen atoms impacting materials placed in low Earth orbit. In this period, we irradiated well over 2000 material samples with 8 km/s oxygen atoms generated in our source. Typical irradiance level is 3 x 10(exp 20) O atoms/sq cm although some materials have been irradiated to fluence levels as high as 6 x 10(exp 21) O atoms/sq cm. The operating principles and characteristics of our source are reviewed along with diagnostic and handling procedures appropriate to material testing. Representative data is presented on the velocity dependence of oxygen atom erosion rates (the PSI source provides oxygen atoms tunable over the velocity range of 5 to 12 km/s) as well as the dependence on material temperature. Specific examples of non-linear oxidative effects related to surface contamination and test duration are also be provided.

  14. Effects of the low Earth orbital environment on spacecraft materials

    NASA Technical Reports Server (NTRS)

    Leger, L. J.

    1986-01-01

    It is evident from space flights during the last three years that the low Earth orbital (LEO) environment interacts with spacecraft surfaces in significant ways. One manifestation of these interactions is recession of, in particular, organic-polymer-based surfaces presumably due to oxidation by atomic oxygen, the major component of the LEO environment. Three experiments have been conducted on Space Shuttle flights 5, 8 and 41-G to measure reaction rates and the effects of various parameters on reaction rates. Surface recession on these flights indicates reaction efficiencies approximately 3 x 10(-24) cu cm/atoms for unfilled organic polymers. Of the metals, silver and osmium are very reactive. Effects on spacecraft or experiment surfaces can be evaluated using the derived reaction efficiencies and a definition of the total exposure to atomic oxygen. This exposure is obtained using an ambient density model, solar activity data and spacecraft parameters of altitude, attitude and operational date. Oxygen flux on a given surface is obtained from the ambient density and spacecraft velocity and can then be integrated to provide the total exposure or fluence. Such information can be generated using simple computational programs and can be converted to various formats. Overall, the extent of damage is strongly dependent on the type of surface and total exposure time.

  15. An electrorotation technique for measuring the dielectric properties of cells with simultaneous use of negative quadrupolar dielectrophoresis and electrorotation.

    PubMed

    Han, Song-I; Joo, Young-Don; Han, Ki-Ho

    2013-03-07

    This paper presents an effective electrorotation technique for measuring the dielectric properties of cells using a superposed electrical signal, which can simultaneously generate negative quadrupolar dielectrophoretic (nQDEP) force and electrorotational (ROT) torque. The proposed technique involves a three-dimensional (3D) octode, which includes four electrodes arranged in a crisscross pattern on the top and bottom of a microchannel, respectively. A single cell was trapped in the center of the 3D octode by the nQDEP force and simultaneously rotated by the ROT torque. Using the proposed electrorotation technique, ROT spectra of human leukocyte subpopulations (T and B lymphocytes, granulocytes, and monocytes) and metastatic human breast (SkBr3) and lung (A549) cancer cell lines were accurately measured without any disturbance. Torque on the cells generated by the ROT signal was analyzed theoretically based on the single-shell dielectric model for the cells. Furthermore, the dielectric properties of the cells, such as area-specific membrane capacitance and cytoplasm conductivity, were extracted using the measured ROT spectra and the analyzed torque.

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

    NASA Astrophysics Data System (ADS)

    Singh, Ram Chandra; Ram, Jokhan

    2011-11-01

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

  17. Investigating FAM-N pulses for signal enhancement in MQMAS NMR of quadrupolar nuclei.

    PubMed

    Colaux, Henri; Dawson, Daniel M; Ashbrook, Sharon E

    2017-01-18

    Although a popular choice for obtaining high-resolution solid-state NMR spectra of quadrupolar nuclei, the inherently low sensitivity of the multiple-quantum magic-angle spinning (MQMAS) experiment has limited its application for nuclei with low receptivity or when the available sample volume is limited. A number of methods have been introduced in the literature to attempt to address this problem. Recently, we have introduced an alternative, automated approach, based on numerical simulations, for generating amplitude-modulated pulses (termed FAM-N pulses) to enhance the efficiency of the triple- to single-quantum conversion step within MQMAS. This results in efficient pulses that can be used without experimental reoptimisation, ensuring that this method is particularly suitable for challenging nuclei and systems. In this work, we investigate the applicability of FAM-N pulses to a wider variety of systems, and their robustness under more challenging experimental conditions. These include experiments performed under fast MAS, nuclei with higher spin quantum numbers, samples with multiple distinct sites, low-γ nuclei and nuclei subject to large quadrupolar interactions.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  19. Modeling dipolar and quadrupolar defect structures generated by chiral islands in freely suspended liquid crystal films.

    PubMed

    Silvestre, N M; Patrício, P; Telo da Gama, M M; Pattanaporkratana, A; Park, C S; Maclennan, J E; Clark, N A

    2009-10-01

    We report a detailed theoretical analysis of quadrupolar interactions observed between islands, which are disklike inclusions of extra layers, floating in thin, freely suspended smectic- C liquid crystal films. Strong tangential anchoring at the island boundaries results in a strength +1 chiral defect in each island and a companion -1 defect in the film--these forming a topological dipole. While islands of the same handedness form linear chains with the topological dipoles pointing in the same direction, as reported in the literature, islands with different handedness form compact quadrupolar structures with the associated dipoles pointing in opposite directions. The interaction between such heterochiral-island-defect pairs is complex, with the defects moving to minimize the director field distortion as the distance between the islands changes. The details of the interisland potential and the trajectories of the -1 defects depend strongly on the elastic anisotropy of the liquid crystal, which can be modified in the experiments by varying the material chirality of the liquid crystal. A Landau model that describes the energetics of freely mobile defects is solved numerically to find equilibrium configurations for a wide range of parameters.

  20. From Order to Chaos in Earth Satellite Orbits

    NASA Astrophysics Data System (ADS)

    Gkolias, Ioannis; Daquin, Jérôme; Gachet, Fabien; Rosengren, Aaron J.

    2016-11-01

    We consider Earth satellite orbits in the range of semimajor axes where the perturbing effects of Earth’s oblateness and lunisolar gravity are of comparable order. This range covers the medium-Earth orbits (MEO) of the Global Navigation Satellite Systems and the geosynchronous orbits (GEO) of the communication satellites. We recall a secular and quadrupolar model, based on the Milankovitch vector formulation of perturbation theory, which governs the long-term orbital evolution subject to the predominant gravitational interactions. We study the global dynamics of this two-and-a-half degrees-of-freedom Hamiltonian system by means of the fast Lyapunov indicator (FLI), used in a statistical sense. Specifically, we characterize the degree of chaoticity of the action space using angle-averaged normalized FLI maps, thereby overcoming the angle dependencies of the conventional stability maps. Emphasis is placed upon the phase-space structures near secular resonances, which are of primary importance to the space debris community. We confirm and quantify the transition from order to chaos in MEO, stemming from the critical inclinations and find that highly inclined GEO orbits are particularly unstable. Despite their reputed normality, Earth satellite orbits can possess an extraordinarily rich spectrum of dynamical behaviors and, from a mathematical perspective, have all the complications that make them very interesting candidates for testing the modern tools of chaos theory.

  1. Earth curvature and atmospheric refraction effects on radar signal propagation.

    SciTech Connect

    Doerry, Armin Walter

    2013-01-01

    The earth isnt flat, and radar beams dont travel straight. This becomes more noticeable as range increases, particularly at shallow depression/grazing angles. This report explores models for characterizing this behavior.

  2. Observations and Effects of Dipolarization Fronts Observed in Earth's Magnetotail

    NASA Technical Reports Server (NTRS)

    Goldstein, Melvyn L.

    2011-01-01

    Dipolarization fronts in Earth's magnetotail are characterized by sharp jumps in magnetic field, a drop in density, and often follow earthward fast plasma flow. They are commonly detected near the equatorial plane of Earth s tail plasma sheet. Sometimes, but not always, dipolarization fronts are associated with global substorms and auroral brightenings. Both Cluster, THEMIS, and other spacecraft have detected dipolarization fronts in a variety of locations in the magnetotail. Using multi-spacecraft analyses together with simulations, we have investigated the propagation and evolution of some dipolarization events. We have also investigated the acceleration of electrons and ions that results from such magnetic-field changes. In some situations, the velocities of fast earthward flows are comparable to the Alfven speed, indicating that the flow bursts might have been generated by bursty reconnection that occurred tailward of the spacecraft. Based on multi-spacecraft timing analysis, dipolarization fronts are found to propagate mainly earthward at 160-335 km/s and have thicknesses of 900-1500 km, which corresponds to the ion inertial length or gyroradius scale. Following the passage of dipolarization fronts, significant fluctuations are observed in the x and y components of the magnetic field. These peaks in the magnetic field come approximately 1-2 minutes after passage of the dipolarization front. These Bx and By fluctuations propagate primarily dawnward and earthward. Field-aligned electron beams are observed coincident with those magnetic field fluctuations. Non-Maxwellian electron and ion distributions are observed that are associated with the dipolarization that may be unstable to a range of electrostatic and/or whistler instabilities. Enhanced electrostatic broadband noise at frequencies below and near the lower-hybrid frequency is also observed at or very close to these fronts. This broadband noise is thought to play a role in further energizing the particles

  3. Effects of Low Earth Orbit on Docking Seal Materials

    NASA Technical Reports Server (NTRS)

    Imka, Emily C.; Asmar, Olivia C.; deGroh, Henry C., III; Banks, Bruce A.

    2014-01-01

    Spacecraft docking seals are typically made of silicone elastomers. When such seals are exposed to low Earth orbit (LEO) conditions, they can suffer damage from ultraviolet (UV) radiation and atomic oxygen (AO, or monoatomic oxygen, the predominant oxygen species in LEO). An experiment flew on the International Space Station (ISS) to measure the effects of LEO on seal materials S0383-70 and ELA-SA-401 and various mating counterface materials which included anodized aluminum. Samples flown in different orientations received different amounts of UV and AO. The hypotheses were that most of the damage would be from UV, and 10 days or more of exposure in LEO would badly damage the seals. Eighteen seals were exposed for 543 days in ram (windward), zenith (away from Earth), or wake (leeward) orientations, and 15 control samples (not flown) provided undamaged baseline leakage. To determine post-flight leak rates, each of the 33 seals were placed in an O-ring groove of a leak test fixture and pressure tested over time. Resistance temperature detectors (RTDs), pressure transducers, and LabVIEW (National Instruments) programs were used to measure and analyze the temperature and pressure and calculate leakage. Average leakage of control samples was 2.6 x 10(exp -7) lbs/day. LEO exposure did not considerably damage ELA-SA-401. The S0383-70 flight samples leaked at least 10 times more than ELA-SA-401 in all cases except one, demonstrating that ELA-SA-401 may be a more suitable sealing material in LEO. AO caused greater damage than UV; samples in ram orientation (receiving an AO fluence of 4.3 x 10(exp 21) atoms/(sq cm) and in wake (2.9x 10(exp 20) atoms/(sq cm)) leaked more than those in zenith orientation (1.58 x 10(exp 20) atoms/(sq cm)), whereas variations in UV exposure did not seem to affect the samples. Exposure to LEO did less damage to the seals than hypothesized, and the data did not support the conjecture that UV causes more damage than AO.

  4. Satellite Motion Effects on Current Collection in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Zhang, T. X.; Hwang, K. S.; Wu, S. T.; Stone, N. H.; Chang, C. L.; Drobot, A.; Wright, K. H., Jr.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Results from the Tethered Satellite System (TSS) missions unambiguously show that the electrodynamic tether system produced 2 to 3 times the predicted current levels in the tether. The pre-mission predictions were based on the well-known Parker-Murphy (PM) model, which describes the collection of current by an electrically biased satellite in the ionospheric plasma. How the TSS satellite was able to collect 2-3 times the PM current has remained an open question. In the present study, self-consistent potential and motional effects are introduced into the Thompson and Dobrowolny sheath models. As a result, the magnetic field aligned sheath-an essential variable in determining current collection by a satellite-is derived and is shown to be explicitly velocity dependent. The orientation of the satellite's orbital motion relative to the geomagnetic field is also considered in the derivation and a velocity dependent expression for the collected current is obtained. The resulting model provides a realistic treatment of current collection by a satellite in low earth orbit. Moreover, the predictions, using the appropriate parameters for TSS, are in good agreement with the tether currents measured during the TSS-1R mission.

  5. Satellite Motion Effects on Current Collection in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Zhang, T. X.; Hwang, K. S.; Wu, S. T.; Stone, N. H.; Chang, C. L.; Drobot, A.; Wright, K. H., Jr.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Results from the Tethered Satellite System (TSS) missions unambiguously show that the electrodynamic tether system produced 2 to 3 times the predicted current levels in the tether. The pre-mission predictions were based on the well-known Parker-Murphy (PM) model, which describes the collection of current by an electrically biased satellite in the ionospheric plasma. How the TSS satellite was able to collect 2-3 times the PM current has remained an open question. In the present study, self-consistent potential and motional effects are introduced into the Thompson and Dobrowolny sheath models. As a result, the magnetic field aligned sheath-an essential variable in determining current collection by a satellite-is derived and is shown to be explicitly velocity dependent. The orientation of the satellite's orbital motion relative to the geomagnetic field is also considered in the derivation and a velocity dependent expression for the collected current is obtained. The resulting model provides a realistic treatment of current collection by a satellite in low earth orbit. Moreover, the predictions, using the appropriate parameters for TSS, are in good agreement with the tether currents measured during the TSS-1R mission.

  6. Radiation effects on rare earth permanent magnets. Master's thesis

    SciTech Connect

    Luna, H.B.

    1988-06-01

    With continuing improvements in rare earth permanent magnet (REPM) technology, applications for their use are being discovered that were previously not possible. Two such applications for permanent magnets are in focusing elements for linear accelerators and ion sources, and in insertion devices (wigglers and undulators) used to produce synchrotron radiation. However, these magnetic transport elements are subjected to high radiation levels. Consequently, there is considerable interest in the United States and abroad to discover and quantify the effects of radiation on REPMs. Using the Lawrence Livermore National Laboratory (LLNL) 100-MeV Linac, four different samples of REPM were irradiated to one to two gigarads of exposed dose from a bremsstrahlung production target in an attempt to simulate the consequences of beam spills of a high energy primary electron beam. Of the samples irradiated, Sm2Co17 proved to be the most resistant to gamma radiation. The electron transport code CYLTRAN of the Integrated Tiger Series (ITS), which is an electron and photon Monte Carlo simulation code, was used to determine the angular and energy spectra for both electrons and photons produced by the target used at the LLNL Linac.

  7. Effects of simulated rare earth recycling wastewaters on biological nitrification

    SciTech Connect

    Fujita, Yoshiko; Barnes, Joni; Eslamimanesh, Ali; Lencka, Malgorzata M.; Anderko, Andrzej; Riman, Richard E.; Navrotsky, Alexandra

    2015-07-16

    Current efforts to increase domestic availability of rare-earth element (REE) supplies by recycling and expanded ore processing efforts will result in increased generation of associated wastewaters. In some cases disposal to a sewage treatment plant may be favored but plant performance must be maintained. To assess the potential effects of such wastewaters on biological wastewater treatment, model nitrifying organisms Nitrosomonas europaea and Nitrobacter winogradskyi were exposed to simulated wastewaters containing varying levels of yttrium or europium (10, 50 and 100 ppm), and the REE extractant tributyl phosphate (TBP, at 0.1 g/L). Y and Eu additions above 10 ppm inhibited N. europaea activity, even when initially virtually all of the REE was insoluble. The provision of TBP together with Eu increased inhibition of nitrite production by the N. europaea, although TBP alone did not substantially alter nitrifying activity N. winogradskyi was more sensitive to the stimulated wastewaters, with even 10 ppm Eu or Y inducing significant inhibition, and a complete shutdown of nitrifying activity occurred in the presence of the TBP. To analyze the availability of REEs in aqueous solutions, REE solubility has been calculated using the previously developed MSE (Mixed-Solvent Electrolyte) thermodynamic model. The model calculations reveal a strong pH dependence of solubility, which is typically controlled by the precipitation of REE hydroxides but may also be influenced by the formation of a phosphate phase.

  8. Effects of simulated rare earth recycling wastewaters on biological nitrification

    DOE PAGES

    Fujita, Yoshiko; Barnes, Joni; Eslamimanesh, Ali; ...

    2015-07-16

    Current efforts to increase domestic availability of rare-earth element (REE) supplies by recycling and expanded ore processing efforts will result in increased generation of associated wastewaters. In some cases disposal to a sewage treatment plant may be favored but plant performance must be maintained. To assess the potential effects of such wastewaters on biological wastewater treatment, model nitrifying organisms Nitrosomonas europaea and Nitrobacter winogradskyi were exposed to simulated wastewaters containing varying levels of yttrium or europium (10, 50 and 100 ppm), and the REE extractant tributyl phosphate (TBP, at 0.1 g/L). Y and Eu additions above 10 ppm inhibited N.more » europaea activity, even when initially virtually all of the REE was insoluble. The provision of TBP together with Eu increased inhibition of nitrite production by the N. europaea, although TBP alone did not substantially alter nitrifying activity N. winogradskyi was more sensitive to the stimulated wastewaters, with even 10 ppm Eu or Y inducing significant inhibition, and a complete shutdown of nitrifying activity occurred in the presence of the TBP. To analyze the availability of REEs in aqueous solutions, REE solubility has been calculated using the previously developed MSE (Mixed-Solvent Electrolyte) thermodynamic model. The model calculations reveal a strong pH dependence of solubility, which is typically controlled by the precipitation of REE hydroxides but may also be influenced by the formation of a phosphate phase.« less

  9. Effects of Simulated Rare Earth Recycling Wastewaters on Biological Nitrification.

    PubMed

    Fujita, Yoshiko; Barnes, Joni; Eslamimanesh, Ali; Lencka, Malgorzata M; Anderko, Andrzej; Riman, Richard E; Navrotsky, Alexandra

    2015-08-18

    Increasing rare earth element (REE) supplies by recycling and expanded ore processing will result in generation of new wastewaters. In some cases, disposal to a sewage treatment plant may be favored, but plant performance must be maintained. To assess the potential effects of such wastewaters on biological treatment, model nitrifying organisms Nitrosomonas europaea and Nitrobacter winogradskyi were exposed to simulated wastewaters containing varying levels of yttrium or europium (10, 50, and 100 ppm), and the extractant tributyl phosphate (TBP, at 0.1 g/L). Y and Eu additions at 50 and 100 ppm inhibited N. europaea, even when virtually all of the REE was insoluble. Provision of TBP with Eu increased N. europaea inhibition, although TBP alone did not substantially alter activity. For N. winogradskyi cultures, Eu or Y additions at all tested levels induced significant inhibition, and nitrification shut down completely with TBP addition. REE solubility was calculated using the previously developed MSE (Mixed-Solvent Electrolyte) thermodynamic model. The model calculations reveal a strong pH dependence of solubility, typically controlled by the precipitation of REE hydroxides but also likely affected by the formation of unknown phosphate phases, which determined aqueous concentrations experienced by the microorganisms.

  10. Effects of differentiation on the geodynamics of the early Earth

    NASA Astrophysics Data System (ADS)

    Piccolo, Andrea; Kaus, Boris; White, Richard; Johnson, Tim

    2016-04-01

    Archean geodynamic processes are not well understood, but there is general agreement that the mantle potential temperature was higher than present, and that as a consequence significant amounts of melt were produced both in the mantle and any overlying crust. This has likely resulted in crustal differentiation. An early attempt to model the geodynamic effects of differentiation was made by Johnson et al. (2014), who used numerical modeling to investigate the crust production and recycling in conjunction with representative phase diagrams (based on the inferred chemical composition of the primary melt in accordance with the Archean temperature field). The results of the simulations show that the base of the over-thickened primary basaltic crust becomes gravitational unstable due to the mineral assemblage changes. This instability leads to the dripping of dense material into the mantle, which causes an asthenospheric return flow, local partial melting and new primary crust generation that is rapidly recycled in to mantle. Whereas they gave important insights, the previous simulations were simplified in a number of aspects: 1) the rheology employed was viscous, and both elasticity and pressure-dependent plasticity were not considered; 2) extracted mantle melts were 100% transformed into volcanic rocks, whereas on the present day Earth only about 20-30% are volcanic and the remainder is plutonic; 3) the effect of a free surface was not studied in a systematic manner. In order to better understand how these simplifications affect the geodynamic models, we here present additional simulations to study the effects of each of these parameters. Johnson, T.E., Brown, M., Kaus, B., and VanTongeren, J.A., 2014, Delamination and recycling of Archaean crust caused by gravitational instabilities: Nature Geoscience, v. 7, no. 1, p. 47-52, doi: 10.1038/NGEO2019.

  11. Effects of Rare Earth Metals on Steel Microstructures

    PubMed Central

    Pan, Fei; Zhang, Jian; Chen, Hao-Long; Su, Yen-Hsun; Kuo, Chia-Liang; Su, Yen-Hao; Chen, Shin-Hau; Lin, Kuan-Ju; Hsieh, Ping-Hung; Hwang, Weng-Sing

    2016-01-01

    Rare earth metals are used in semiconductors, solar cells and catalysts. This review focuses on the background of oxide metallurgy technologies, the chemical and physical properties of rare earth (RE) metals, the background of oxide metallurgy, the functions of RE metals in steelmaking, and the influences of RE metals on steel microstructures. Future prospects for RE metal applications in steelmaking are also presented. PMID:28773545

  12. Comparison of relativistic effects in barycentric and Earth-centered coordinates and implications for determination of GM for Earth

    NASA Technical Reports Server (NTRS)

    Ashby, Neil

    1987-01-01

    The results of an investigation of relativistic effects which have an influence on the determination of GM sub E (M sub E is the mass of the Earth, G is the Newtonian gravitaional constant) are summarized. The detailed arguments and derivations are discussed. The Parametrized Post-Newtonian (PPN) coordinates; Eddington-Clark (EC) coordinates; a coordinate system based on barycentric dynamical time (TBC coordinates); and Local Inertial coordinates are discussed.

  13. The Effect of the Earth's Atmosphere on LSST Photometry

    SciTech Connect

    Rahlin, Alexandra S.; /MIT /SLAC

    2006-08-30

    The Large Synoptic Survey Telescope (LSST), a ground-based telescope currently under development, will allow a thorough study of dark energy by measuring, more completely and accurately than previously, the rate of expansion of the universe and the large-scale structure of the matter in it. The telescope utilizes a broadband photometric system of six wavelength bands to measure the redshifts of distant objects. The earth's atmosphere makes it difficult to acquire accurate data, since some of the light passing through the atmosphere is scattered or absorbed due to Rayleigh scattering, molecular absorption, and aerosol scattering. Changes in the atmospheric extinction distribution due to each of these three processes were simulated by altering the parameters of a sample atmospheric distribution. Spectral energy distributions of standard stars were used to simulate data acquired by the telescope. The effects of changes in the atmospheric parameters on the photon flux measurements through each wavelength band were observed in order to determine which atmospheric conditions must be monitored most closely to achieve the desired 1% uncertainty on flux values. It was found that changes in the Rayleigh scattering parameter produced the most significant variations in the data; therefore, the molecular volume density (pressure) must be measured with at most 8% uncertainty. The molecular absorption parameters produced less significant variations and could be measured with at most 62% uncertainty. The aerosol scattering parameters produced almost negligible variations in the data and could be measured with > 100% uncertainty. These atmospheric effects were found to be almost independent of the redshift of the light source. The results of this study will aid the design of the atmospheric monitoring systems for the LSST.

  14. Separation of isotropic chemical and second-order quadrupolar shifts by multiple-quantum double rotation NMR.

    PubMed

    Hung, Ivan; Wong, Alan; Howes, Andy P; Anupõld, Tiit; Samoson, Ago; Smith, Mark E; Holland, Diane; Brown, Steven P; Dupree, Ray

    2009-04-01

    Using a two-dimensional multiple-quantum (MQ) double rotation (DOR) experiment the contributions of the chemical shift and quadrupolar interaction to isotropic resonance shifts can be completely separated. Spectra were acquired using a three-pulse triple-quantum z-filtered pulse sequence and subsequently sheared along both the nu(1) and nu(2) dimensions. The application of this method is demonstrated for both crystalline (RbNO(3)) and amorphous samples (vitreous B(2)O(3)). The existence of the two rubidium isotopes ((85)Rb and (87)Rb) allows comparison of results for two nuclei with different spins (I=3/2 and 5/2), as well as different dipole and quadrupole moments in a single chemical compound. Being only limited by homogeneous line broadening and sample crystallinity, linewidths of approximately 0.1 and 0.2 ppm can be measured for (87)Rb in the quadrupolar and chemical shift dimensions, enabling highly accurate determination of the isotropic chemical shift and the quadrupolar product, P(Q). For vitreous B(2)O(3), the use of MQDOR allows the chemical shift and electric field gradient distributions to be directly determined-information that is difficult to obtain otherwise due to the presence of second-order quadrupolar broadening.

  15. Second-order quadrupolar line shapes under molecular dynamics: An additional transition in the extremely fast regime.

    PubMed

    Hung, Ivan; Wu, Gang; Gan, Zhehong

    2016-12-10

    NMR spectroscopy is a powerful tool for probing molecular dynamics. For the classic case of two-site exchange, NMR spectra go through the transition from exchange broadening through coalescence and then motional narrowing as the exchange rate increases passing through the difference between the resonance frequencies of the two sites. For central-transition spectra of half-integer quadrupolar nuclei in solids, line shape change due to molecular dynamics occurs in two stages. The first stage occurs when the exchange rate is comparable to the second-order quadrupolar interaction. The second spectral transition comes at a faster exchange rate which approaches the Larmor frequency and generally reduces the isotropic quadrupolar shift. Such a two-stage transition phenomenon is unique to half-integer quadrupolar nuclei. A quantum mechanical formalism in full Liouville space is presented to explain the physical origin of the two-stage phenomenon and for use in spectral simulations. Variable-temperature (17)O NMR of solid NaNO3 in which the NO3(-) ion undergoes 3-fold jumps confirms the two-stage transition process. The spectra of NaNO3 acquired in the temperature range of 173-413K agree well with simulations using the quantum mechanical formalism. The rate constants for the 3-fold NO3(-) ion jumps span eight orders of magnitude (10(2)-10(10)s(-1)) covering both transitions of the dynamic (17)O line shape.

  16. Static quadrupolar susceptibility for a Blume-Emery-Griffiths model based on the mean-field approximation

    NASA Astrophysics Data System (ADS)

    Pawlak, A.; Gülpınar, G.; Erdem, R.; Ağartıoğlu, M.

    2015-12-01

    The expressions for the dipolar and quadrupolar susceptibilities are obtained within the mean-field approximation in the Blume-Emery-Griffiths model. Temperature as well as crystal field dependences of the susceptibilities are investigated for two different phase diagram topologies which take place for K/J=3 and K/J=5.0.Their behavior near the second and first order transition points as well as multi-critical points such as tricritical, triple and critical endpoint is presented. It is found that in addition to the jumps connected with the phase transitions there are broad peaks in the quadrupolar susceptibility. It is indicated that these broad peaks lie on a prolongation of the first-order line from a triple point to a critical point ending the line of first-order transitions between two distinct paramagnetic phases. It is argued that the broad peaks are a reminiscence of very strong quadrupolar fluctuations at the critical point. The results reveal the fact that near ferromagnetic-paramagnetic phase transitions the quadrupolar susceptibility generally shows a jump whereas near the phase transition between two distinct paramagnetic phases it is an edge-like.

  17. Unusual locations of Earth`s bow shock on September 24-25, 1987: Mach number effects

    SciTech Connect

    Cairns, I.H.; Anderson, R.R.; Fairfield, D.H.; Carlton, V.E.H.; Paularena, K.I.; Lazarus, A.J.

    1995-01-01

    ISEE 1 and IMP 8 data are used to identify 19 crossings of Earth`s bow shock during a 30-hour period following 0000 UT on September 24, 1987. Apparent standoff distances for the shock are calculated for each crossing using two methods and the spacecraft location; one method assumes the average shock shape, while the other assumes a ram pressure-dependent shock shape. The shock`s apparent standoff distance normally {approximately}14 R{sub E}, is shown to increase from near 10 R{sub E} initially to near 19 R{sub E}. The Alfven M{sub A} and fast magnetosonic M{sub ms} Mach numbers remain above 2 and the number density above 4 cm{sup {minus}3} for almost the entire period. Ram pressure effects produce the initial near-Earth shock location, whereas expansions and contractions of the bow shock due to low Mach number effects account, qualitatively and semiquantitatively, for the timing and existence of almost all the remaining ISEE crossings and both IMP 8 crossings. Ram pressure-induced changes in the shock`s shape are discussed but found to be quantitatively unimportant for the shock crossings analyzed. Approximate estimates of both the deviation of the shock`s standoff distance from the standard model and of the shock`s shape are determined independently (but not consistently) for M{sub ms}{approximately}2.4. The estimates imply substantial changes in standoff distance and/or shock shape at low M{sub A} and M{sub ms}. Mach number effects can therefore be quantitatively important in determining and predicting the shape and location of the bow shock, even when M{sub A} and M{sub ms} remain above 2. This study confirms and generalizes previous studies of Mach number effects on Earth`s bow shock. Statistical studies and simulations of the bow shock`s shape and location should be performed as a function of Mach number, magnetic field orientation, and ram pressure. 25 refs., 12 figs.

  18. Bremsstrahlung radiation effects in rare earth permanent magnets

    SciTech Connect

    Luna, H.; Maruyama, X.; Colella, N.; Hobbs, J.; Hornady, R.; Kulke, B.; Palomar, J.

    1988-12-15

    Advances in rare earth permanent magnet (REPM) technology have made possible new applications. Two such applications are the use of permanent magnetic lenses for accelerator and beam transport systems and the expanding use in undulators and wigglers of synchrotron radiation and free electron laser systems. Both applications involve potential exposure of REPM's to high radiation fields. We have investigated the radiation hardness of several different varieties of REPM's up to 2 gigarads of absorbed dose from a mixed electron-photon (bremsstrahlung) field. Sm/sub 2/Co/sub 17/, Nd/sub 2/Fe/sub 14/B and an experimental REPM, Pr/sub 15/Fe/sub 79/B/sub 6/, from several different manufacturers have been investigated. Of the samples irradiated, Sm/sub 2/Co/sub 17/ proved to be the most resistant to bremsstrahlung radiation. However, details of manufacturing techniques produced significantly different results. We observed that REPM's of nominally identical stoichiometric composition from different manufacturers did not show the same rate of remanence loss. We present details of our experiment and absorbed dose modeling and a summary of radiation effects measurements of which we are aware. Our study of these radiation damage experiments lead us to the empirical observation that the order of radiation hardness is Sm/sub 2/Co/sub 17/, SmCo/sub 5/ and Nd/sub 2/Fe/sub 14/B, regardless of the source of radiation, i.e., gammas, electrons, protons or neutrons. 8 refs., 2 figs., 4 tabs.

  19. Solar rotation effects on the thermospheres of Mars and Earth.

    PubMed

    Forbes, Jeffrey M; Bruinsma, Sean; Lemoine, Frank G

    2006-06-02

    The responses of Earth's and Mars' thermospheres to the quasi-periodic (27-day) variation of solar flux due to solar rotation were measured contemporaneously, revealing that this response is twice as large for Earth as for Mars. Per typical 20-unit change in 10.7-centimeter radio flux (used as a proxy for extreme ultraviolet flux) reaching each planet, we found temperature changes of 42.0 +/- 8.0 kelvin and 19.2 +/- 3.6 kelvin for Earth and Mars, respectively. Existing data for Venus indicate values of 3.6 +/- 0.6 kelvin. Our observational result constrains comparative planetary thermosphere simulations and may help resolve existing uncertainties in thermal balance processes, particularly CO2 cooling.

  20. The effect of aerosols on the earth-atmosphere albedo

    NASA Technical Reports Server (NTRS)

    Herman, B. M.; Browning, S. R.

    1975-01-01

    The paper presents calculations of the change in reflected flux by the earth-atmosphere system in response to increases in the atmospheric aerosol loading for a range of complex indices of refraction, solar elevation angle and ground albedo. Results show that, for small values of ground albedo, the reflected solar flux may either increase or decrease with increasing aerosol loadings, depending upon the complex part of the index of refraction of the aerosols. For high ground albedos, an increase in aerosol levels always results in a decrease of reflected flux (i.e., a warming of the earth-atmosphere system).

  1. COLORS OF A SECOND EARTH. II. EFFECTS OF CLOUDS ON PHOTOMETRIC CHARACTERIZATION OF EARTH-LIKE EXOPLANETS

    SciTech Connect

    Fujii, Yuka; Suto, Yasushi; Turner, Edwin L.; Kawahara, Hajime; Fukuda, Satoru; Nakajima, Teruyuki; Livengood, Timothy A.

    2011-09-10

    As a test bed for future investigations of directly imaged terrestrial exoplanets, we present the recovery of the surface components of the Earth from multi-band diurnal light curves obtained with the EPOXI spacecraft. We find that the presence and longitudinal distribution of ocean, soil, and vegetation are reasonably well reproduced by fitting the observed color variations with a simplified model composed of a priori known albedo spectra of ocean, soil, vegetation, snow, and clouds. The effect of atmosphere, including clouds, on light scattered from surface components is modeled using a radiative transfer code. The required noise levels for future observations of exoplanets are also determined. Our model-dependent approach allows us to infer the presence of major elements of the planet (in the case of the Earth, clouds, and ocean) with observations having signal-to-noise ratio (S/N) {approx}> 10 in most cases and with high confidence if S/N {approx}> 20. In addition, S/N {approx}> 100 enables us to detect the presence of components other than ocean and clouds in a fairly model-independent way. Degradation of our inversion procedure produced by cloud cover is also quantified. While cloud cover significantly dilutes the magnitude of color variations compared with the cloudless case, the pattern of color changes remains. Therefore, the possibility of investigating surface features through light-curve fitting remains even for exoplanets with cloud cover similar to Earth's.

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

    PubMed

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  4. Resonance excitation of ions stored in a quadrupole ion trap. Part IV. Theory of quadrupolar excitation

    NASA Astrophysics Data System (ADS)

    Alfred, Roland L.; Londry, Frank A.; March, Raymond E.

    1993-06-01

    A new theoretical treatment is presented for quadrupolar resonance excitation of ions stored in a quadrupole ion trap. When the ratio of the tickle voltage amplitude to that of the drive potential is small, the equation of ion motion can be expressed in the form of a perturbation series. Exact and approximate solutions to the first-order perturbation eqations are presented. Ion trajectories calculated from these solutions are compared with those calculated by numerical integration. The resonance conditions were found to correspond to a series of angular frequencies given by [omega]u,n = n + [beta]u - [infinity] < n < [infinity]. Some of these, [beta]z[Omega], (1 + [beta]z)[Omega](1 - [beta]z)[Omega] [beta],[Omega], had been observed previously in simulation studies.

  5. Implementing SPAM into STMAS: A net sensitivity improvement in high-resolution NMR of quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Amoureux, J. P.; Delevoye, L.; Fink, G.; Taulelle, F.; Flambard, A.; Montagne, L.

    2005-08-01

    Gan and Kwak recently introduced two new tools for high-resolution 2D NMR methods applied to quadrupolar nuclei: double-quantum filtering in STMAS (DQF-STMAS) and the soft-pulse added mixing (SPAM) idea. Double-quantum filtering suppresses all undesired signals in the STMAS method with limited loss in sensitivity. With SPAM, all pathways are added constructively after the second hard-pulse instead of using a single pathway as previously. Here, the sensitivity, advantages and drawbacks of DQF-STMAS are compared to 3QMAS. Additionally, SPAM can be included into DQF-STMAS method, resulting in a net sensitivity gain with respect to 3QMAS of ca. 10-15.

  6. Implementing SPAM into STMAS: a net sensitivity improvement in high-resolution NMR of quadrupolar nuclei.

    PubMed

    Amoureux, J P; Delevoye, L; Fink, G; Taulelle, F; Flambard, A; Montagne, L

    2005-08-01

    Gan and Kwak recently introduced two new tools for high-resolution 2D NMR methods applied to quadrupolar nuclei: double-quantum filtering in STMAS (DQF-STMAS) and the soft-pulse added mixing (SPAM) idea. Double-quantum filtering suppresses all undesired signals in the STMAS method with limited loss in sensitivity. With SPAM, all pathways are added constructively after the second hard-pulse instead of using a single pathway as previously. Here, the sensitivity, advantages and drawbacks of DQF-STMAS are compared to 3QMAS. Additionally, SPAM can be included into DQF-STMAS method, resulting in a net sensitivity gain with respect to 3QMAS of ca. 10-15.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  8. Earth regeneration effect in solar neutrino oscillations: An analytic approach

    SciTech Connect

    Lisi, E.; Montanino, D.

    1997-08-01

    We present a simple and accurate method for computing analytically the regeneration probability of solar neutrinos in the Earth. We apply this method to the calculation of several solar-model-independent quantities that can be measured by the SuperKamiokande and Sudbury Neutrino Observatory experiments. {copyright} {ital 1997} {ital The American Physical Society}

  9. Best Mitigation Paths To Effectively Reduce Earth's Orbital Debris

    NASA Technical Reports Server (NTRS)

    Wiegman, Bruce M.

    2009-01-01

    This slide presentation reviews some ways to reduce the problem posed by debris in orbit around the Earth. It reviews the orbital debris environment, the near-term needs to minimize the Kessler syndrome, also known as collisional cascading, a survey of active orbital debris mitigation strategies, the best paths to actively remove orbital debris, and technologies that are required for active debris mitigation.

  10. Tidal effects on Earth, Planets, Sun by far visiting moons

    NASA Astrophysics Data System (ADS)

    Fargion, Daniele

    2016-07-01

    The Earth has been formed by a huge mini-planet collision forming our Earth surface and our Moon today. Such a central collision hit was statistically rare. A much probable skimming or nearby encounter by other moons or planets had to occur. Indeed Recent observations suggest that many planetary-mass objects may be present in the outer solar system between the Kuiper belt and the Oort cloud. Gravitational perturbations may occasionally bring them into the inner solar system. Their passage near Earth could have generated gigantic tidal waves, large volcanic eruptions, sea regressions, large meteoritic impacts and drastic changes in global climate. They could have caused the major biological mass extinctions in the past in the geological records. For instance a ten times a terrestrial radius nearby impact scattering by a peripherical encounter by a small moon-like object will force huge tidal waves (hundred meter height), able to lead to huge tsunami and Earth-quake. Moreover the historical cumulative planet hits in larger and wider planets as Juppiter, Saturn, Uranus will leave a trace, as observed, in their tilted spin axis. Finally a large fraction of counter rotating moons in our solar system probe and test such a visiting mini-planet captur origination. In addition the Earth day duration variability in the early past did show a rare discountinuity, very probably indebt to such a visiting planet crossing event. These far planets in rare trajectory to our Sun may, in thousands event capture, also explain sudden historical and recent temperature changes.

  11. The Impenetrable Barrier Revisited - Anthroprogenic Effects on Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Foster, J. C.; Baker, D. N.; Erickson, P. J.; Albert, J.; Fennell, J. F.; Mishin, E. V.; Starks, M. J.; Jaynes, A. N.; Li, X.; Kanekal, S. G.; Kletzing, C.

    2015-12-01

    The Van Allen Probes are contributing significantly to the understanding of processes effecting Earth's radiation belts. It has been noted that the earthward extent of the outer zone highly-relativistic electrons encounters a nearly impenetrable barrier at a radial distance (L) near 2.8 RE inside of which they are not observed. Modeling suggests that this is the result of a balance between slow inward diffusion and hiss-induced precipitation. The large storm of 17 March 2015 afforded an excellent opportunity to investigate the impenetrable barrier using the full complement of sensors carried by the Van Allen Probes. The storm was marked by the rapid reappearance of strong fluxes of MeV electrons directly outside the barrier with the formation of very steep MeV flux gradients. In spite of the strong rapid recovery of MeV electron fluxes immediately outside the barrier, the sharpness and constancy of the gradient at the barrier is strongly suggestive of a previously unrecognized fast-acting and spatially localized mechanism responsible for the formation of such a well-defined feature during these dramatic circumstances. The Van Allen Probes regularly observe a magnetically confined bubble of VLF emissions of terrestrial origin filling the inner magnetosphere. Strongest signals are from US Navy VLF transmitters used for one-way communication to submarines. These signals largely are confined to the region of L space where their frequency is < ½ fce. The strong signal from station NAA at 24 kHz is confined to L < 2.8 where it encounters the ½ fce limit. During the event, the flux of MeV electrons decreased by 1000x across 0.5 RE outside L = 2.8 simultaneous with a 6 order of magnitude increase in the VLF wave intensity as the Probes entered the VLF bubble. The VLF transmitter frequencies are amplified at the point where they overlap natural chorus band near ½ fce suggestive of transmitter-induced triggered emissions. MeV radiation belt electrons encounter this

  12. Analysis of earth albedo effect on sun sensor measurements based on theoretical model and mission experience

    NASA Technical Reports Server (NTRS)

    Brasoveanu, Dan; Sedlak, Joseph

    1998-01-01

    Analysis of flight data from previous missions indicates that anomalous Sun sensor readings could be caused by Earth albedo interference. A previous Sun sensor study presented a detailed mathematical model of this effect. The model can be used to study the effect of both diffusive and specular reflections and to improve Sun angle determination based on perturbed Sun sensor measurements, satellite position, and an approximate knowledge of attitude. The model predicts that diffuse reflected light can cause errors of up to 10 degrees in Coarse Sun Sensor (CSS) measurements and 5 to 10 arc sec in Fine Sun Sensor (FSS) measurements, depending on spacecraft orbit and attitude. The accuracy of these sensors is affected as long as part of the illuminated Earth surface is present in the sensor field of view. Digital Sun Sensors (DSS) respond in a different manner to the Earth albedo interference. Most of the time DSS measurements are not affected, but for brief periods of time the Earth albedo can cause errors which are a multiple of the sensor least significant bit and may exceed one degree. This paper compares model predictions with Tropical Rainfall Measuring Mission (TRMM) CSS measurements in order to validate and refine the model. Methods of reducing and mitigating the impact of Earth albedo are discussed. ne CSS sensor errors are roughly proportional to the Earth albedo coefficient. Photocells that are sensitive only to ultraviolet emissions would reduce the effective Earth albedo by up to a thousand times, virtually eliminating all errors caused by Earth albedo interference.

  13. Effects of Superthermal Electrons in The Young Earth Atmosphere and Its Habitability

    NASA Astrophysics Data System (ADS)

    Airapetian, V.; Khazanov, G. V.

    2014-12-01

    In this presentation, we use the Fokker-Plank code to model the effect of intensive short-wavelength (X-rays to UV band) emission from the young Sun on Earth's atmosphere. Our simulations include the photoionization processes of the Earth's atmosphere forming a population of superthermal electrons (E<600 eV), the kinetic effects of their propagation associated and their contribution in ionosphere-magnetosphere energy redistribution. We also evaluated associated non-thermal atmospheric mass loss due to induced ambipolar electric field and its effect on the habitability of early Earth.

  14. The Effect of Fulvic Acid on the Leaching of a Weathered Rare-Earth Ore

    NASA Astrophysics Data System (ADS)

    Luo, Xian-ping; Feng, Bo; Wang, Peng-cheng; Zhou, He-peng; Chen, Xiao-ming

    2015-12-01

    The effect of fulvic acid on the leaching of a weathered crust elution-deposited rare-earth ore, using ammonium sulfate as lixiviant, has been investigated. The results show that fulvic acid can enhance the leaching process effectively. With the addition of fulvic acid to the lixiviant at a concentration of 0.1 wt pct, the leaching extraction of rare-earth elements increased by 8.38 pct and the ammonium sulfate concentration decreased by 25 wt pct. Fulvic acid promotes the leaching process. It also reacts with rare-earth ions, forms soluble complexes, reduces the activity of the leached rare-earth ions, and increases the concentration difference of ion diffusion. These results highlight a new approach for making the leaching process of low-grade weathered crust elution-deposited rare-earth ore more efficient and also for lowering the lixiviant consumption.

  15. The effect of the earth's rotation on ground water motion.

    PubMed

    Loáiciga, Hugo A

    2007-01-01

    The average pore velocity of ground water according to Darcy's law is a function of the fluid pressure gradient and the gravitational force (per unit volume of ground water) and of aquifer properties. There is also an acceleration exerted on ground water that arises from the Earth's rotation. The magnitude and direction of this rotation-induced force are determined in exact mathematical form in this article. It is calculated that the gravitational force is at least 300 times larger than the largest rotation-induced force anywhere on Earth, the latter force being maximal along the equator and approximately equal to 34 N/m(3) there. This compares with a gravitational force of approximately 10(4) N/m(3).

  16. Some observations on the greenhouse effect at the Earth's surface.

    PubMed

    Akitt, J W

    2018-01-05

    It is shown that the greenhouse gases carbon dioxide and water vapour reflect back to the surface, all IR radiation originating at the surface within their respective spectral bands. This reflection occurs in a very thin layer at the surface, not much over 12cm in thickness. Heat is lost from the surface by heat exchange with the atmosphere and by loss of radiation. About 52% of radiation leaves the surface in two principal window regions but this is not enough to account for the earth's equilibrium temperature. This window radiation seems to disappear quite quickly and is replaced by black body radiation. It is this which eventually contributes to the earth's radiation balance, and has to originate approximately between 40 and 50km altitude where the temperature is about correct, near 255K. Doubling the CO2 concentration increases the surface temperature by about 0.9°C and this need not have any influence higher up in the atmosphere. The surface temperature seems indeed to have no direct influence on the earth's external radiation balance. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Single Event Effects Testing For Low Earth Orbit Missions with Neutrons

    NASA Technical Reports Server (NTRS)

    Reddell, Brandon; O'Neill, Pat; Bailey, Chuck; Nguyen, Kyson

    2015-01-01

    Neutrons can effectively be used to screen electronic parts intended to be used in Low Earth Orbit. This paper compares neutron with proton environments in spacecraft and discusses recent comparison testing.

  18. Telluric currents have no significant effect on the Earth's core seismicity

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.

    2017-01-01

    We show that telluric currents have no effect on the formation of macrofaults in the Earth's crust or on implementation of the intensification regime. This is mainly associated with the weakness of telluric currents and induction of the geomagnetic field.

  19. Materials resistance to low earth orbit environmental effects

    NASA Technical Reports Server (NTRS)

    Pippin, H. G.; Torre, L. P.; Linton, R. G.; Whitaker, A. F.

    1989-01-01

    A number of flexible polymeric materials have been considered as condidates for protective coatings on Kapton film. These coatings have been tested under a variety of environments, each of which simulates one or more aspects of the low earth orbit space environment. Mass loss rates vs fluence and temperatue, optical properties, and surface characteristics under exposure to the various environments will be presented. Kinetics data on Kapton and other materials is interpreted in terms of bond strengths and relative thermodynamic stabilities of potential products. Activation energy for degradation of Kapton by oxygen atoms was determined to be 30 + or - 5 kJ/mol. Materials tested include silicones, fluorosilicones, fluorophosphazenes, fluorocarbons, and hydrocarbons.

  20. Nonequilibrium effects on shock-layer radiometry during earth entry.

    NASA Technical Reports Server (NTRS)

    Arnold, J. O.; Whiting, E. E.

    1973-01-01

    Radiative enhancement factors for the CN violet and N2(+) first negative band systems caused by nonequilibrium thermochemistry in the shock layer of a blunt-nosed vehicle during earth entry are reported. The results are based on radiometric measurements obtained with the aid of a combustion-driven shock tube. The technique of converting the shock-tube measurements into predictions of the enhancement factors for the blunt-body case is described, showing it to be useful for similar applications of other shock-tube measurements.

  1. Study of effects of space power satellites on life support functions of the earth's magnetosphere

    NASA Technical Reports Server (NTRS)

    Douglas, M.; Laquey, R.; Deforest, S. E.; Lindsey, C.; Warshaw, H.

    1977-01-01

    The effects of the Satellite Solar Power System (SSPS) on the life support functions of the earth's magnetosphere were investigated. Topics considered include: (1) thruster effluent effects on the magnetosphere; (2) biological consequences of SSPS reflected light; (3) impact on earth bound astronomy; (4) catastrophic failure and debris; (5) satellite induced processes; and (6) microwave power transmission. Several impacts are identified and recommendations for further studies are provided.

  2. An Assessment of Relativistic Effects for Low Earth Orbiters: The GRACE Satellites

    DTIC Science & Technology

    2007-01-01

    IOP PUBLISHING METROLOGIA Metrologia 44 (2007) 484–490 doi:10.1088/0026-1394/44/6/007 An assessment of relativistic effects for low Earth orbiters...for the larger-eccentricity orbit is shown in figure 2(b). Metrologia , 44 (2007) 484–490 485 K M Larson et al Figure 1. Amplitude of the once/rev...486 Metrologia , 44 (2007) 484–490 Assessment of relativistic effects for low Earth orbiters combination was launched on TOPEX in 1992. Unfortunately

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

    PubMed

    Tzvetkova, Pavleta; Luy, Burkhard

    2016-05-01

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

  4. Chemical effects of large impacts on the Earth's primitive atmosphere.

    PubMed

    Fegley, B; Prinn, R G; Hartman, H; Watkins, G H

    1986-01-23

    Intense bombardment of the moon and terrestrial planets approximately 3.9-4.0 x 10(9) years ago could have caused the chemical reprocessing of the Earth's primitive atmosphere. In particular, the shock heating and rapid quenching caused by the impact of large bodies into the atmosphere could produce molecules such as HCN and H2CO4 which are important precursors for the abiotic synthesis of complex organic molecules. Here we model the production of HCN and H2CO by thermochemical equilibrium and chemical kinetic calculations of the composition of shocked air parcels for a wide range of temperatures, pressures and initial compositions. For atmospheres with C/O > or = 1, our results suggest that bolide impacts cause HCN volume mixing ratios of approximately 10(-3) to 10(-5) in the impact region and global average ratios of 10(-5) to 10(-12). The corresponding H2CO mixing ratios in the impact region are 10(-7) to 10(-9); no-global mixing can occur, however, as H2CO is rapidly destroyed or rained out of the atmosphere within days to hours. Rainout to the oceans of 3-15% of the HCN produced can provide approximately (3-14) x 10(11) mol HCN per year. This is somewhat larger than other predicted sources of HCN and H2CO on the primitive Earth.

  5. The effect of EarthPulse on learning of declarative knowledge

    NASA Astrophysics Data System (ADS)

    McKinney, Heather E.

    The purpose of this double-blind, bio-medical research study was to investigate the effect of EarthPulse, a brainwave entrainment and pulsed electromagnetic field (PEMF) device, on learning of declarative knowledge. Currently, PEMF research explores physiological and psychological effects but a gap exists in the potential effects of PEMF on learning. The study explored whether a relationship existed between receiving a thirty minute EarthPulse treatment on the "Entrain Up" setting and learning of declarative knowledge; whether the relationship remained over time; whether EarthPulse had an effect on sleep; and whether EarthPulse had an effect on attrition. Ninety-eight, randomly assigned, undergraduate students participated in this double-blind, experimental design study, of which 87 remained after attrition. After receiving a thirty minute EarthPulse or placebo treatment, experimental and control groups read identical passages and completed identical instruments to test learning and retention of declarative knowledge. Participants completed the same test in two intervals: an immediate (learning) and delayed (retention) posttest. Assumptions for normality and reliability were met. One-way ANOVA revealed no statistically significant effects on learning or retention at the 0.05 level. However, Chi square analysis revealed those who received the EarthPulse treatment were significantly less likely to fall asleep than those who received the control treatment (p=0.022) and very closely approached significance for attrition (p=0.051).

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

    NASA Astrophysics Data System (ADS)

    Li, Xiaohua

    1999-11-01

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

  7. The Effect of Rare Earth on the Structure and Performance of Laser Clad Coatings

    NASA Astrophysics Data System (ADS)

    Bao, Ruiliang; Yu, Huijun; Chen, Chuanzhong; Dong, Qing

    Laser cladding is one kind of advanced surface modification technology and has the abroad prospect in making the wear-resistant coating on metal substrates. However, the application of laser cladding technology does not achieve the people's expectation in the practical production because of many defects such as cracks, pores and so on. The addiction of rare earth can effectively reduce the number of cracks in the clad coating and enhance the coating wear-resistance. In the paper, the effects of rare earth on metallurgical quality, microstructure, phase structure and wear-resistance are analyzed in turns. The preliminary discussion is also carried out on the effect mechanism of rare earth. At last, the development tendency of rare earth in the laser cladding has been briefly elaborated.

  8. Solid-state NMR spectroscopy of the quadrupolar halogens: chlorine-35/37, bromine-79/81, and iodine-127.

    PubMed

    Bryce, David L; Sward, Gregory D

    2006-04-01

    A thorough review of 35/37Cl, 79/81Br, and 127I solid-state nuclear magnetic resonance (SSNMR) data is presented. Isotropic chemical shifts (CS), quadrupolar coupling constants, and other available information on the magnitude and orientation of the CS and electric field gradient (EFG) tensors for chlorine, bromine, and iodine in diverse chemical compounds is tabulated on the basis of over 200 references. Our coverage is through July 2005. Special emphasis is placed on the information available from the study of powdered diamagnetic solids in high magnetic fields. Our survey indicates a recent notable increase in the number of applications of solid-state quadrupolar halogen NMR, particularly 35Cl NMR, as high magnetic fields have become more widely available to solid-state NMR spectroscopists. We conclude with an assessment of possible future directions for research involving 35/37Cl, 79/81Br, and 127I solid-state NMR spectroscopy.

  9. 2H 2O quadrupolar splitting used to measure water exchange in erythrocytes

    NASA Astrophysics Data System (ADS)

    Kuchel, Philip W.; Naumann, Christoph

    2008-05-01

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

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

    PubMed

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

    2016-04-01

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

  11. Discover Earth

    NASA Technical Reports Server (NTRS)

    Steele, Colleen

    1998-01-01

    Discover Earth is a NASA-sponsored project for teachers of grades 5-12, designed to: (1) enhance understanding of the Earth as an integrated system; (2) enhance the interdisciplinary approach to science instruction; and (3) provide classroom materials that focus on those goals. Discover Earth is conducted by the Institute for Global Environmental Strategies in collaboration with Dr. Eric Barron, Director, Earth System Science Center, The Pennsylvania State University; and Dr. Robert Hudson, Chair, the Department of Meteorology, University of Maryland at College Park. The enclosed materials: (1) represent only part of the Discover Earth materials; (2) were developed by classroom teachers who are participating in the Discover Earth project; (3) utilize an investigative approach and on-line data; and (4) can be effectively adjusted to classrooms with greater/without technology access. The Discover Earth classroom materials focus on the Earth system and key issues of global climate change including topics such as the greenhouse effect, clouds and Earth's radiation balance, surface hydrology and land cover, and volcanoes and climate change. All the materials developed to date are available on line at (http://www.strategies.org) You are encouraged to submit comments and recommendations about these materials to the Discover Earth project manager, contact information is listed below. You are welcome to duplicate all these materials.

  12. On the observability of 'out-of-plane' quadrupolar magnetic perturbations in two-dimensional force-free reconnection

    SciTech Connect

    Wang Jiaqi; Wang Xiaogang

    2008-09-15

    Nonlinear studies for 'out-of-plane' magnetic perturbations in two-dimensional force-free magnetic reconnection are carried out to analyze if they are significant enough to be observable in concerned regimes. It is found that though in linear analysis [Bian et al., Phys. Plasmas 14, 120702 (2007)] the 'out-of-plane' quadrupolar magnetic perturbation can be generated in the 'standard magnetohydrodynamics regime', it is too weak to be detected in observations.

  13. Glacier Melting Effect on the Earth's Rotation - Revisited

    NASA Astrophysics Data System (ADS)

    Na, S. H.; Sahagian, D. L.; Kim, T. H.; Jo, B. G.; Ahn, K. D.; Shin, Y. H.

    2014-12-01

    The direction of polar wander has recently been tilted eastward by several degrees. By direct calculation of Earth's inertia tensor perturbation due to observed glacier mass changes (twenty year average), we found the yearly drift polar motion excitation as (ψ1, ψ2)=(1.00, 0.05) milliarcsec. This direction closely matches the observed pole drift, and we infer that glacier melting is the primary driver of the observed polar wander. Analysis of polar motion data indicates that a substantial portion of the observed eastward pole drift has occurred since the late 1990s, also consistent with the accelerated rate of glacier melting. The associated change in LOD due to average glacier melting for the last twenty years is estimated as +114 microsec, which implies total 0.42 s delay in UT1 for the same time span.

  14. Quadrupolar nutation NMR to discriminate central and satellite transitions: Spectral assignments for a Ziegler-Natta catalyst

    NASA Astrophysics Data System (ADS)

    Blaakmeer, E. S. (Merijn); Franssen, Wouter M. J.; Kentgens, Arno P. M.

    2017-08-01

    In this contribution we used solid state 35 Cl (I = 3/2) quadrupolar NMR to study a MgCl2/2,2-dimethyl-1,3-dimethoxypropane (DMDOMe) adduct that serves as a model system for Ziegler-Natta catalysis. Employing large Radio-Frequency (RF) field strengths we observe three spectral features with strongly varying line widths. The assignment of the spectra is complicated because of the large difference in quadrupolar interactions experienced by the different sites in the system. The satellite transitions (ST) of relatively well-defined bulk Cl sites are partially excited and may overlap with the central transition (CT) resonances of more distorted surface sites. We show that nutation NMR of the ST of I = 3/2 spins yields a unique pattern that makes a clear distinction between an extensively broadened central transition and the satellite transitions of a component with a smaller quadrupolar interaction. This allows us to unambiguously unravel the spectra of the MgCl2 adduct showing that we observe CT and ST of the bulk phase of MgCl2-nanoparticles with a CQ of 4.6 MHz together with the CT of surface sites displaying an average CQ of ∼ 10 MHz.

  15. Resonant and static cubic hyperpolarizabilities of push-pull dipolar and quadrupolar chromophores: toward enhanced two-photon absorption

    NASA Astrophysics Data System (ADS)

    Barzoukas, Marguerite; Blanchard-Desce, Mireille H.

    2001-12-01

    Recent reports of push-pull dipolar and quadrupolar chromophores with enhanced two-photon absorption have generated considerable interest in these two molecular systems. Two photon absorption is related to the imaginary part of the two-photon resonant cubic hyperpolarizability Im[(gamma) ((omega) )]. In this work, we have described both push-pull dipolar and quadrupolar chromophores using multi valence-bond states models based on measurable parameters of the valence-bond forms. We have derived analytical expressions of their non-resonant static cubic hyperpolarizability (gamma) (0) and of Im[(gamma) ((omega) )]. Comparison between the transparency / Im[(gamma) ((omega) )] trade-off and Im[(gamma) ((omega) )] / (gamma) (0) correlation helps understand the advantages and drawbacks of each of these two push-pull systems. Furthermore by understanding how the valence-bond parameters are related to the molecular structure and its environment, it is possible to predict how Im[(gamma) ((omega) )] will be affected by changing either the conjugation size, the donor-acceptor pair or the solvent polarity for both of these push-pull systems. The results of this study suggest common guidelines for the molecular engineering of both the push-pull dipolar and quadrupolar chromophores.

  16. Biological effects of high ultraviolet radiation on early earth--a theoretical evaluation.

    PubMed

    Cockell, C S

    1998-08-21

    The surface of early Earth was exposed to both UVC radiation (< 280 nm) and higher doses of UVB (280-315 nm) compared with the surface of present day Earth. The degree to which this radiation environment acted as a selection pressure on organisms and biological systems has rarely been theoretically examined with respect to the biologically effective irradiances that ancient organisms would receive. Here action spectra for DNA inactivation and isolated chloroplast inhibition are used to estimate biologically effective irradiances on archean Earth. Comparisons are made with present day Earth. The theoretical estimations on the UV radiation screening required to protect DNA on archean Earth compare well with field and laboratory observations on protection strategies found in present day microbial communities. They suggest that many physical and biological methods may have been effective and would have allowed for the radiation of life even under the high UV radiation regimes of archean Earth. Such strategies would also have provided effective reduction of photoinhibition by UV radiation. The data also suggest that the UV regime on the surface of Mars is not a life limiting factor per se, although other environmental factors such as desiccation and low temperatures may contribute towards the apparent lack of a surface biota.

  17. Effect of alkaline-earth ions on the dynamics of alkali ions in bismuthate glasses

    NASA Astrophysics Data System (ADS)

    Dutta, A.; Ghosh, A.

    2005-12-01

    The effect of alkaline earth ions on the dynamics of Li+ ions in bismuthate glasses has been studied in the temperature range 353-503K and in the frequency range 10Hz-2MHz . The dc conductivity increases and activation energy decreases with the increase of a particular alkaline earth content for the glasses with a fixed alkali content. The increased modification of the network due to the increase in alkaline earth content in the compositions is responsible for the increasing conductivity. Also the compositions with smaller alkaline earth ions were found to exhibit higher conductivity. Although the conductivity increases with the decrease of ionic radii of alkaline earth ions, the activation energy shows a maximum for the Sr ion. The electric modulus and the conductivity formalisms have been employed to study the relaxation dynamics of charge carriers in these glasses. The alkali ions were observed to change their dynamics with the change of the alkaline earth ions. The same anomalous trend for activation energy for the conductivity relaxation frequency and the hopping frequency was also observed for glasses containing SrO. It was also observed that the mobile lithium ion concentrations are independent of nature of alkaline earth ions in these glasses.

  18. Nuclear magnetic resonance of J-coupled quadrupolar nuclei: Use of the tensor operator product basis

    NASA Astrophysics Data System (ADS)

    Kemp-Harper, R.; Philp, D. J.; Kuchel, P. W.

    2001-08-01

    In nuclear magnetic resonance (NMR) of I=1/2 nuclei that are scalar coupled to quadrupolar spins, a tensor operator product (TOP) basis set provides a convenient description of the time evolution of the density operator. Expressions for the evolution of equivalent I=1/2 spins, coupled to an arbitrary spin S>1/2, were obtained by explicit algebraic density operator calculations in Mathematica, and specific examples are given for S=1 and S=3/2. Tensor operators are described by the convenient quantum numbers rank and order and this imparts to the TOP basis features that enable an intuitive understanding of NMR behavior of these spin systems. It is shown that evolution as a result of J coupling alone changes the rank of tensors for the coupling partner, generating higher-rank tensors, which allow efficient excitation of S-spin multiple-quantum coherences. Theoretical predictions obtained using the TOP formalism were confirmed using multiple-quantum filtered heteronuclear spin-echo experiments and were further employed to demonstrate polarization transfer directly to multiple-quantum transitions using the insensitive nucleus enhancement by polarization transfer pulse sequence. This latter experiment is the basis of two-dimensional heteronuclear correlation experiments and direct generation of multiple-quantum S-spin coherences can therefore be exploited to yield greater spectral resolution in such experiments. Simulated spectra and experimental results are presented.

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

    PubMed

    Gao, Zhongxing; Zhang, Yonggang; Zhang, Yunhao

    2016-07-21

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

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

    PubMed Central

    Gao, Zhongxing; Zhang, Yonggang; Zhang, Yunhao

    2016-01-01

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

  1. Quadrupolar NMR Relaxation from ab Initio Molecular Dynamics: Improved Sampling and Cluster Models versus Periodic Calculations.

    PubMed

    Philips, Adam; Marchenko, Alex; Truflandier, Lionel A; Autschbach, Jochen

    2017-09-12

    Quadrupolar NMR relaxation rates are computed for (17)O and (2)H nuclei of liquid water, and of (23)Na(+), and (35)Cl(-) in aqueous solution via Kohn-Sham (KS) density functional theory ab initio molecular dynamics (aiMD) and subsequent KS electric field gradient (EFG) calculations along the trajectories. The calculated relaxation rates are within about a factor of 2 of experimental results and improved over previous aiMD simulations. The relaxation rates are assessed with regard to the lengths of the simulations as well as configurational sampling. The latter is found to be the more limiting factor in obtaining good statistical sampling and is improved by averaging over many equivalent nuclei of a system or over several independent trajectories. Further, full periodic plane-wave basis calculations of the EFGs are compared with molecular-cluster atomic-orbital basis calculations. The two methods deliver comparable results with nonhybrid functionals. With the molecular-cluster approach, a larger variety of electronic structure methods is available. For chloride, the EFG computations benefit from using a hybrid KS functional.

  2. Collective water dynamics in the first solvation shell drive the NMR relaxation of aqueous quadrupolar cations

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Using molecular simulations, we analyze the microscopic processes driving the Nuclear Magnetic Resonance (NMR) relaxation of quadrupolar cations in water. The fluctuations of the Electric Field Gradient (EFG) experienced by alkaline and magnesium cations, which determine the NMR relaxation time, are mainly due to the dynamics of water molecules in their solvation shell. The dynamics of the ion plays a less important role, with the exception of the short-time dynamics in the lighter Li+ case, for which rattling in the solvent cage results in oscillations of the EFG autocorrelation function (ACF). Several microscopic mechanisms that may a priori contribute to the decay of the EFG-ACF occur in fact over too long time scales: entrance/exit of individual water molecules into/from the solvation shell, rotation of a molecule around the ion, or reorientation of the molecule. In contrast, the fluctuations of the ion-water distance are clearly correlated to that of the EFG. Nevertheless, it is not sufficient to consider a single molecule due to the cancellations arising from the symmetry of the solvation shell. The decay of the EFG-ACF, hence NMR relaxation, is in fact governed by the collective symmetry-breaking fluctuations of water in the first solvation shell.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  4. Mixed-mode solitons in quadrupolar BECs with spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Chen, Guihua; Liu, Yan; Wang, Hongcheng

    2017-07-01

    We show families of two-dimensional (2D) composite solitons in spinor quadrupolar Bose-Einstein condensates, with two localized components linearly mixed by the spin-orbit coupling (SOC), and the intrinsic nonlinearity represented by the quadrupole-quadrupole interaction (QQI) between atomic electric quadrupole moments perpendicular to the system's plane by an external electric field. Recently, stable solitons were predicted in the form of mixed mode (composites built of mixed fundamental and vortical components) in the 2D system combining the SOC and contact attractive interactions. Replacing the latter by the anisotropic long-range QQI, we demonstrate that, for a fixed norm, the system supports a continuous family of stable mixed-mode solitons (MMSs), parameterized by different norm distribution between two components. The chemical potential of the MMSs does not depend on the norm distribution, which shows a highly degeneracy. In order to identify these degenerate solitons, a magnetic field could be applied to the system. In the present system, with the Galilean invariance broken by the SOC, the composite solitons are set in motion by a kick, and we find that the motions of solitons along x and y directions are almost coupling to each other (A kick in x or y direction can probably cause a motion including x and y components). Moreover, by simulation, we also find that semi-vortex solitons (with a vortex in one component and a fundamental soliton in the other) can be supported in our model.

  5. Effects of Iron Partitioning on Earth's Magma Ocean

    NASA Astrophysics Data System (ADS)

    Ricard, Y. R.; Boukare, C. E.

    2016-12-01

    Present deep Earth mantle structures such as ultralow-velocity zones (ULVZs) and large low-shear velocity provinces (LLSVPs) may be directly linked to the crystallization of magma ocean. This scenario is mainly based on the generation of iron-rich dense material by fractionnal crystallization very early in the Earth's history. The generation of iron-rich materials at the bottom of the mantle is supported by experimental studies that show iron preferentially partitions into melts at all mantle depths. Since it has also been reported that melts are more compressible than solids, we need to better constrain the generation and buoyancy of such iron-rich materials at deep mantle conditions. Because iron content affects both the buoyancy and melting temperature of sillicate materials, this process might also affect the dynamics of a crystallizing system. A solid-liquid thermodynamic database for silicates in the MgO-FeO-SiO2 system from 20 GPa to 140 GPa has been constructed [Boukare et al., 2015]. We compute the ternary phase diagram in the MgO-FeO-SiO2 system as a function of temperature and pressure. This self-consistent approach allows us to predict crystallization sequences at deep mantle conditions. We confirm that the melt is lighter than a solid with same composition for all mantle conditions. However, due to iron partitioning, the iron-rich liquid is denser than the solid in the deep mantle. To understand the complex dynamics associated with these potential density cross-overs between melts and solids, we have developed a multiphase phase numerical code. It can simultaneously handle the convection of each phase. In crystal-rich regions, it calculates the compaction or decompaction of the two phases. Although our code can only run in a parameter range (Rayleigh number, viscosity contrast between phases, Prandlt number) far from what would be realistic, it produces rich dynamics that illustrate potential physical and chemical processes. We show situations in which

  6. The effects of phase boundary induced layering on the Earth's thermal history

    NASA Astrophysics Data System (ADS)

    Butler, S. L.

    2009-12-01

    The convective Urey ratio is equal to the instantaneous heating generated in the Earth's mantle by radioactive decay divided by the contribution of convection in Earth's mantle to Earth's surface heat flow. The measured heat flow at the Earth's surface as well as geochemical models for radioactive abundances give relatively low modern-day convective Urey ratios of roughly 0.4 while early parameterized modelling studies that treated the internal heating rate as a free parameter indicated relatively high modern-day Urey ratios of at least 0.6. Seismic tomographic images of subducting slabs and numerical simulations of convection in Earth's mantle indicate that convection is partially layered by the endothermic phase transition at 660-km depth in the mantle. In numerical simulations, the 660-km depth phase transition also leads to increased time-dependence of the mantle flow and mantle `avalanches'. Incomplete layering has been proposed as a mechanism that could store heat in Earth's lower mantle early in Earth's evolution and release it at later times when the degree of layering decreases thus allowing for the modern-day surface heat flow with a relatively low internal heating rate. In this contribution, the Earth's thermal history is simulated using both dynamic models of mantle circulation that include the effects of the mantle phase transitions and parametrized models of mantle heat transfer. In particular, we will show that for dynamic models with Earth-like parameters describing the 660-km-depth phase boundary that, although the mass flux at 660-km depth is partially impeded and avalanching takes place, the long-term evolution of the surface heat flow is very similar to models with no phase boundary induced layering and hence incomplete mantle layering is not a likely solution of the mantle heat flow paradox.

  7. The effect of clouds on the earth's radiation budget

    NASA Technical Reports Server (NTRS)

    Ziskin, Daniel; Strobel, Darrell F.

    1991-01-01

    The radiative fluxes from the Earth Radiation Budget Experiment (ERBE) and the cloud properties from the International Satellite Cloud Climatology Project (ISCCP) over Indonesia for the months of June and July of 1985 and 1986 were analyzed to determine the cloud sensitivity coefficients. The method involved a linear least squares regression between co-incident flux and cloud coverage measurements. The calculated slope is identified as the cloud sensitivity. It was found that the correlations between the total cloud fraction and radiation parameters were modest. However, correlations between cloud fraction and IR flux were improved by separating clouds by height. Likewise, correlations between the visible flux and cloud fractions were improved by distinguishing clouds based on optical depth. Calculating correlations between the net fluxes and either height or optical depth segregated cloud fractions were somewhat improved. When clouds were classified in terms of their height and optical depth, correlations among all the radiation components were improved. Mean cloud sensitivities based on the regression of radiative fluxes against height and optical depth separated cloud types are presented. Results are compared to a one-dimensional radiation model with a simple cloud parameterization scheme.

  8. Effect of limb darkening on earth radiation incident on a spherical satellite

    NASA Technical Reports Server (NTRS)

    Katzoff, S.; Smith, G. L.

    1974-01-01

    The thermal radiation from the earth incident on a spherical satellite depends on the angular distribution of earth-emitted radiation. An analysis is presented of this dependency, and calculated results are given, based on a published limb-darkening curve for the earth. The curve was determined from Tiros data, and is a statistical average over the entire globe between 75 deg latitude. The computed effect of limb darkening was 1.8 percent at 900 km altitude, 2.5 percent at 500 km altitude, and 3.0 percent at 300 km altitude. Below 300 km, it increased rapidly with decreasing altitude. Discussion is included of various other problems inherent in the use of orbiting spheres and stabilized flat plates to measure the heat radiated from the earth.

  9. Effects of Rare-Earth Oxides on the Reliability of X7R Dielectrics

    NASA Astrophysics Data System (ADS)

    Sakabe, Yukio; Hamaji, Yukio; Sano, Harunobu; Wada, Nobuyuki

    2002-09-01

    The effects of rare-earth oxides, e.g., La, Nd, Sm, Dy and Yb, on the reliability of multilayer capacitors (MLCs) with X7R dielectrics and Ni electrodes were investigated. Microstructures of the dielectrics were analyzed by transmission electron microscopy (TEM) and electron probe microanalysis (EPMA) in order to characterize the rare-earth ions. Incorporation of rare-earth ions to BaTiO3 ceramics depended on their ionic radius, resulting in different microstructures and electric performances of dielectrics. Dy ions provided BaTiO3 ceramics with ideal X7R characteristics and high reliability. The mechanism governing leakage current was discussed in terms of the voltage dependence of leakage current. Electric properties and related reliability of the capacitors were attributed to solubility, distribution of rare-earth oxides and their occupation site in BaTiO3.

  10. Effects of selective fusion on the thermal history of the earth's mantle

    USGS Publications Warehouse

    Lee, W.H.K.

    1968-01-01

    A comparative study on the thermal history of the earth's mantle was made by numerical solutions of the heat equation including and excluding selective fusion of silicates. Selective fusion was approximated by melting in a multicomponent system and redistribution of radioactive elements. Effects of selective fusion on the thermal models are (1) lowering (by several hundred degrees centigrade) and stabilizing the internal temperature distribution, and (2) increasing the surface heat-flow. It was found that models with selective fusion gave results more compatible with observations of both present temperature and surface heat-flow. The results therefore suggest continuous differentiation of the earth's mantle throughout geologic time, and support the hypothesis that the earth's atmosphere, oceans, and crust have been accumulated throughout the earth's history by degassing and selective fusion of the mantle. ?? 1968.

  11. Using the Earth as an Effective Model for Integrating Space Science Into Education Outreach Programs

    NASA Astrophysics Data System (ADS)

    Morris, P. A.; Allen, J.; Galindo, C.; McKay, G.; Obot, V.; Reiff, P.

    2005-05-01

    Our methods of teaching Earth and space science as two disciplines do not represent the spirit of earlier scientists such as Aristotle, da Vinci, and Galileo. We need to re-evaluate these methods and take advantage of the excitement created in the general public over the recent space science exploration programs. The information that we are obtaining from both the Mars missions and Cassini-Huygens focuses on interpreting geomorphology, mineral compositions and gas identification based on Earth as a baseline for data evaluation. This type of evaluation is an extension of Hutton's 18th century principle of Uniformitarianism, the present is the key to the past, or Earth is the key for understanding extraterrestrial bodies. Geomorphological examples are volcanic activity, meteoritic impacts, and evidence of water altering surface features. The Hawaiian, or shield, type volcanoes are analogues for Olympus Mons and the other volcanoes on Mars. Other examples include comparing sand dunes on Earth with possible Martian dunes, known stream patterns on Earth with potential stream patterns on Mars, and even comparing meteoritic impact features on Mars, the Earth, Moon and Mercury. All of these comparisons have been developed into inquiry-based activities and are available through NASA publications. Each of these activities is easily adapted to emphasize either Earth science or space science or both. Beyond geomorphology, solar storms are an excellent topic for integrating Earth and space science. Solar storms are traditionally part of space science studies, but most students do not understand their effect on Earth or the intense effects they could have on humans, whether traveling through space or exploring the surfaces of the Moon or Mars. Effects are not only limited to space travel and other planetary surfaces but also include Earth's magnetosphere, which in turn, affect radio transmission and potentially climate. Like geomorphology courses, there are extensive NASA

  12. Perceived Barriers and Strategies to Effective Online Earth and Space Science Instruction

    NASA Astrophysics Data System (ADS)

    Pottinger, James E.

    With the continual growth and demand of online courses, higher education institutions are attempting to meet the needs of today's learners by modifying and developing new student centered services and programs. As a result, faculty members are being forced into teaching online, including Earth and Space science faculty. Online Earth and Space science courses are different than typical online courses in that they need to incorporate an inquiry-based component to ensure students fully understand the course concepts and science principles in the Earth and Space sciences. Studies have addressed the barriers in other inquiry-based online science courses, including biology, physics, and chemistry. This holistic, multiple-case qualitative study investigated perceived barriers and strategies to effective online Earth and Space science instruction through in-depth interviews with six experienced post-secondary online science instructors. Data from this study was analyzed using a thematic analysis approach and revealed four common themes when teaching online Earth and Space science. A positive perception and philosophy of online teaching is essential, the instructor-student interaction is dynamic, course structure and design modification will occur, and online lab activities must make science operational and relevant. The findings in this study demonstrated that online Earth and Space science instructors need institutional support in the form of a strong faculty development program and support staff in order to be as effective as possible. From this study, instructors realize that the instructor-student relationship and course structure is paramount, especially when teaching online science with labs. A final understanding from this study was that online Earth and Space science lab activities must incorporate the use and application of scientific skills and knowledge. Recommendations for future research include (a) qualitative research conducted in specific areas within the

  13. Effect of the shrinking dipole on solar-terrestrial energy input to the Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    McPherron, R. L.

    2011-12-01

    The global average temperature of the Earth is rising rapidly. This rise is primarily attributed to the release of greenhouse gases as a result of human activity. However, it has been argued that changes in radiation from the Sun might play a role. Most energy input to the Earth is light in the visible spectrum. Our best measurements suggest this power input has been constant for the last 40 years (the space age) apart from a small 11-year variation due to the solar cycle of sunspot activity. Another possible energy input from the Sun is the solar wind. The supersonic solar wind carries the magnetic field of the Sun into the solar system. As it passes the Earth it can connect to the Earth's magnetic field whenever it is antiparallel t the Earth's field. This connection allows mass, momentum, and energy from the solar wind to enter the magnetosphere producing geomagnetic activity. Ultimately much of this energy is deposited at high latitudes in the form of particle precipitation (aurora) and heating by electrical currents. Although the energy input by this process is miniscule compared to that from visible radiation it might alter the absorption of visible radiation. Two other processes affected by the solar cycle are atmospheric entry of galactic cosmic rays (GCR) and solar energetic protons (SEP). A weak solar magnetic field at sunspot minimum facilitates GCR entry which has been implicated in creation of clouds. Large coronal mass ejections and solar flares create SEP at solar maximum. All of these alternative energy inputs and their effects depend on the strength of the Earth's magnetic field. Currently the Earth's field is decreasing rapidly and conceivably might reverse polarity in 1000 years. In this paper we describe the changes in the Earth's magnetic field and how this might affect GCR, SEP, electrical heating, aurora, and radio propagation. Whether these effects are important in global climate change can only be determined by detailed physical models.

  14. Relativity mission with two counter-orbiting polar satellites. [nodal dragging effect on earth orbiting satellites

    NASA Technical Reports Server (NTRS)

    Van Patten, R. A.; Everitt, C. W. F.

    1975-01-01

    In 1918, J. Lense and H. Thirring calculated that a moon in orbit around a massive rotating planet would experience a nodal dragging effect due to general relativity. We describe an experiment to measure this effect with two counter-orbiting drag-free satellites in polar earth orbit. For a 2 1/2 year experiment, the measurement accuracy should approach 1%. In addition to precision tracking data from existing ground stations, satellite-to-satellite Doppler ranging data are taken at points of passing near the poles. New geophysical information on both earth harmonics and tidal effects is inherent in the polar ranging data.

  15. Effect of Solar Variability on Earth Climate Patterns.

    NASA Astrophysics Data System (ADS)

    Ruzmaikin, A.; Feynman, J.

    2006-12-01

    We discuss the impact of solar variability on the patterns of Earth climate variability. These climate patterns are naturally excited in the noisy atmosphere-ocean dynamical system as deviations (anomalies) from a global (mean) state. The patterns include North Atlantic Oscillation (NAO) and related Northern Annular Mode (NAM), Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO). An example of a pattern influenced by variations in solar UV irradiance is the NAM, a wintertime climate anomaly with two states corresponding to higher pressure at high latitudes with a band of lower pressure at lower latitudes and the other way round (Thompson &Wallace, 1998). Two states of the NAM arise due to the dynamical interaction of planetary waves and zonal mean wind (Limpasuvan &Hartmann, 2001; Ruzmaikin et al., 2006). The NAM accounts for 23% of atmospheric variability at sea level and about 50% of the variability in the stratosphere. Solar variability affects the NAM and that the influence varies dependent on the phase of the Quasi Biennial Oscillation and time in the winter season (Ruzmaikin &Feynman, 2002). The temperature pattern (cold in Europe-warm in Greenland) produced by the negative NAM was dominant during the Maunder Minimum of solar activity (Ruzmaikin et al., 2004). We discuss possible physical mechanisms by which solar variability can influence the climate patterns. In particular, we address the Rossby-Palmer hypothesis (Palmer, 1998) that external forcing (in our case solar variability) may affect only the magnitude of the pattern variability without changing its spatial structure. References: Thompson, D. W. J. &J. M. Wallace, Geophys. Res. Lett., 25, 1297, 1998; Palmer, T. N., Bull. Amer. Meteor. Soc., 79, 1412 1998; Baldwin, M. P. and T. J. Dunkerton, J. Geophys. Res. 104, 30,937, 1999; Limpasuvan, V., &D. Hartmann, J. Climate, 13, 4414, 2001; Ruzmaikin, A., J, Feynman, J. Geophys. Res., 107, D14, 10

  16. Titan's Greenhouse Effect And Climate: Lessons From The Earth's Cooler Cousin

    NASA Astrophysics Data System (ADS)

    Nixon, Conor A.; Titan Climate White Paper Proposal Team

    2009-12-01

    We argue that continuing scientific study of Earth's `distant cousin’ Titan can provide a greater understanding and insight into the energy balance of our own planet's atmosphere. Titan's Earth-like properties have been recognized for some time, from the discovery of its atmosphere in 1907, through the Voyager 1 encounter in 1980 that showed Titan's atmosphere is mostly nitrogen gas with a surface pressure within a factor of two of terrestrial. Calculation shows that Titan's atmosphere causes `greenhouse’ warming of the surface, an effect similar to that seen on the Earth, Mars, and Venus. In the 1990s, direct imaging from the Earth by adaptive optics revealed that Titan's ubiquitous haze layer is slowly changing in apparent response to the seasons that occur due to the Saturn system's obliquity. The NASA Cassini mission that arrived in Saturnian orbit in 2004, and the ESA Huygens Titan probe of 2005, have returned a flood of new data regarding this intriguing world. For the first time, we are building a detailed picture of weather in the lower atmosphere, where condensable methane takes on the role played by water in the Earth's atmosphere, leading to methane rainfall, rivers and lakes. We examine parallels between the atmospheres of Earth and of Titan, including the possibilities for dramatic climate change. Extending the duration of the Cassini spacecraft mission during the next decade will provide part of the needed picture, but in addition we urge planning for a future new mission focused on Titan's climate, and other measures.

  17. The effect of SST emissions on the earth's ozone layer

    NASA Technical Reports Server (NTRS)

    Whitten, R. C.; Turco, R. P.

    1974-01-01

    The work presented here is directed toward assessment of environmental effects of the supersonic transport (SST). The model used for the purpose includes vertical eddy transport and the photochemistry of the O-H-N system. It is found that the flight altitude has a pronounced effect on ozone depletion. The largest ozone reduction occurs for NO deposition above an altitude of 20 km.

  18. Removal of barometric pressure effects and earth tides from observed water levels.

    PubMed

    Toll, Nathanial J; Rasmussen, Todd C

    2007-01-01

    The effects of barometric pressure and earth tide changes are often observed in ground water level measurements. These disturbances can make aquifer test interpretation difficult by masking the small changes induced by aquifer testing at late times and great distances. A computer utility is now available that automatically removes the effects of barometric pressure and earth tides from water level observations using regression deconvolution. This procedure has been shown to remove more noise then traditional constant barometric efficiency techniques in both confined and unconfined aquifers. Instead of a single, instantaneous barometric efficiency, the procedure more correctly accounts for the lagged responses caused by barometric pressure and earth tide changes. Simultaneous measurements of water levels (or total heads) and nearby barometric pressures are required. As an additional option, the effects of earth tides can also be removed using theoretical earth tides. The program is demonstrated for two data sets collected at the Waste Isolation Pilot Plant, Carlsbad, New Mexico. The program is available free by request at http://www.hydrology.uga.edu/tools.html.

  19. Plasma and magnetic field variations in the distant magnetotail associated with near-earth substorm effects

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Bame, S. J.; Mccomas, D. J.; Zwickl, R. D.; Slavin, J. A.; Smith, E. J.

    1987-01-01

    Examination of many individual event periods in the ISEE 3 deep-tail data set has suggested that magnetospheric substorms produce a characteristic pattern of effects in the distant magnetotail. During the growth, or tail-energy-storage phase of substorms, the magnetotail appears to grow diametrically in size, often by many earth radii. Subsequently, after the substorm expansive phase onset at earth, the distant tail undergoes a sequence of plasma, field, and energetic-particle variations as large-scale plasmoids move rapidly down the tail following their disconnection from the near-earth plasma sheet. ISEE 3 data are appropriate for the study of these effects since the spacecraft remained fixed within the nominal tail location for long periods. Using newly available auroral electrojet indices (AE and AL) and Geo particle data to time substorm onsets at earth, superposed epoch analyses of ISEE 3 and near-earth data prior to, and following, substorm expansive phase onsets have been performed. These analyses quantify and extend substantially the understanding of the deep-tail pattern of response to global substorm-induced dynamical effects.

  20. Earth tides

    SciTech Connect

    Harrison, J.C.

    1984-01-01

    Nineteen papers on gravity, tilt, and strain tides are compiled into this volume. Detailed chapters cover the calculation of the tidal forces and of the Earth's response to them, as well as actual observations of earth tides. Partial Contents: On Earth tides. The tidal forces: Tidal Forces. New Computations of the Tide-Generating Potential. Corrected Tables of Tidal Harmonics. The Theory of Tidal Deformations. Body Tides on an Elliptical, Rotating, Elastic and Oceanless Earth, Deformation of the Earth by Surface Loads. Gravimetric Tidal Loading Computed from Integrated Green's Functions. Tidal Friction in the Solid Earth. Loading Tides Versus Body Tides. Lunar Tidal Acceleration from Earth Satellite Orbit Analysis. Observations: gravity. Tidal Gravity in Britain: Tidal Loading and the Spatial Distribution of the Marine Tide. Tidal Loading along a Profile Europe-East Africa-South Asia-Australia and the Pacific Ocean. Detailed Gravity-Tide Spectrum between One and Four Cycles per Day. Observations: tilt and strain. Cavity and Topographic Effects in Tilt and Strain Measurement. Observations of Local Elastic Effects on Earth Tide Tilts and Strains.

  1. Relativistic Effect on Multiplet Terms of Rare Earth Ions

    NASA Astrophysics Data System (ADS)

    Itoh, Shinichi; Saito, Riichiro; Kimura, Tadamasa; Yabushita, Satoshi

    1994-02-01

    Ab initio Spin-Orbit Configuration Interaction (SOCI) calculations for the trivalent lanthanide group ions are presented for the special purpose to investigate the relativistic SO effects on their multiplet terms. The effective nuclear charges (Z eff's) for one-body spin-orbit Hamiltonian are calculated by an atomic Dirac-Slater Xα equation and applied to the lanthanide ions. The relativistic effects of core electrons can easily be included in the reduction of Z eff and the multiplet levels shift up to 200 cm-1 by the reduction. The multiplet energies obtained by the present method are in good agreement with experimental values.

  2. Induced quadrupolar singlet ground state of praseodymium in a modulated pyrochlore

    NASA Astrophysics Data System (ADS)

    van Duijn, J.; Kim, K. H.; Hur, N.; Ruiz-Bustos, R.; Adroja, D. T.; Bridges, F.; Daoud-Aladine, A.; Fernandez-Alonso, F.; Wen, J. J.; Kearney, V.; Huang, Q. Z.; Cheong, S.-W.; Perring, T. G.; Broholm, C.

    2017-09-01

    The complex structure and magnetism of Pr2 -xBixRu2O7 was investigated by neutron scattering and extended x-ray absorption fine structure. Pr has an approximate doublet ground state and the first excited state is a singlet. While the B -site (Ru) is well ordered throughout, this is not the case for the A -site (Pr/Bi). A broadened distribution for the Pr-O2 bond length at low temperature indicates the Pr environment varies from site to site even for x =0 . The environment about the Bi site is highly disordered ostensibly due to the 6 s lone pairs on Bi3 +. Correspondingly, we find that the non-Kramers doublet ground-state degeneracy, otherwise anticipated for Pr in the pyrochlore structure, is lifted so as to produce a quadrupolar singlet ground state with a spatially varying energy gap. For x =0 , below TN, the Ru sublattice orders antiferromagnetically, with propagation vector k =(0 ,0 ,0 ) as for Y2Ru2O7 . No ordering associated with the Pr sublattice is observed down to 100 mK. The low-energy magnetic response of Pr2 -xBixRu2O7 features a broad spectrum of magnetic excitations associated with inhomogeneous splitting of the Pr quasidoublet ground state. For x =0 (x =0.97 ), the spectrum is temperature dependent (independent). It appears disorder associated with Bi alloying enhances the inhomogeneous Pr crystal-field level splitting so that intersite interactions become irrelevant for x =0.97 . The structural complexity for the A -site may be reflected in the hysteretic uniform magnetization of B -site ruthenium in the Néel phase.

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

    NASA Astrophysics Data System (ADS)

    Filippov, Boris; Koutchmy, Serge; Tavabi, Ehsan

    2013-08-01

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

  4. Spectroscopic characterization and modeling of quadrupolar charge-transfer dyes with bulky substituents.

    PubMed

    Sissa, Cristina; Terenziani, Francesca; Painelli, Anna; Siram, Raja Bhaskar Kanth; Patil, Satish

    2012-04-26

    Joint experimental and theoretical work is presented on two quadrupolar D-π-A-π-D chromophores characterized by the same bulky donor (D) group and two different central cores. The first chromophore, a newly synthesized species with a malononitrile-based acceptor (A) group, has a V-shaped structure that makes its absorption spectrum very broad, covering most of the visible region. The second chromophore has a squaraine-based core and therefore a linear structure, as also evinced from its absorption spectra. Both chromophores show an anomalous red shift of the absorption band upon increasing solvent polarity, a feature that is ascribed to the large, bulky structure of the molecules. For these molecules, the basic description of polar solvation in terms of a uniform reaction field fails. Indeed, a simple extension of the model to account for two independent reaction fields associated with the two molecular arms quantitatively reproduces the observed linear absorption and fluorescence as well as fluorescence anisotropy spectra, fully rationalizing their nontrivial dependence on solvent polarity. The model derived from the analysis of linear spectra is adopted to predict nonlinear spectra and specifically hyper-Rayleigh scattering and two-photon absorption spectra. In polar solvents, the V-shaped chromophore is predicted to have a large HRS response in a wide spectral region (approximately 600-1300 nm). Anomalously large and largely solvent-dependent HRS responses for the linear chromophores are ascribed to symmetry lowering induced by polar solvation and amplified in this bulky system by the presence of two reaction fields.

  5. Climatic effects due to halogenated compounds in the earth's atmosphere

    NASA Technical Reports Server (NTRS)

    Wang, W.-C.; Pinto, J. P.; Yung, Y. L.

    1980-01-01

    Using a one-dimensional radiative-convective model, a sensitivity study is performed of the effect of ozone depletion in the stratosphere on the surface temperature. There could be a cooling of the surface temperature by approximately 0.2 K due to chlorofluoromethane-induced ozone depletion at steady state (assuming 1973 release rates). This cooling reduces significantly the greenhouse effect due to the presence of chlorofluoromethanes. Carbon tetrafluoride has a strong nu sub 3 band at 7.8 microns, and the atmospheric greenhouse effect is shown to be 0.07 and 0.12 K/ppbv with and without taking into account overlap with CH4 and N2O bands. At concentrations higher than 1 ppbv, absorption by the nu sub 3 band starts to saturate and the greenhouse effect becomes less efficient.

  6. Thulium anomalies and rare earth element patterns in meteorites and Earth: Nebular fractionation and the nugget effect

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Pourmand, Ali

    2015-08-01

    This study reports the bulk rare earth element (REEs, La-Lu) compositions of 41 chondrites, including 32 falls and 9 finds from carbonaceous (CI, CM, CO and CV), enstatite (EH and EL) and ordinary (H, L and LL) groups, as well as 2 enstatite achondrites (aubrite). The measurements were done in dynamic mode using multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS), allowing precise quantification of mono-isotopic REEs (Pr, Tb, Ho and Tm). The CI-chondrite-normalized REE patterns (LaN/LuN; a proxy for fractionation of light vs. heavy REEs) and Eu anomalies in ordinary and enstatite chondrites show more scatter in more metamorphosed (petrologic types 4-6) than in unequilibrated (types 1-3) chondrites. This is due to parent-body redistribution of the REEs in various carrier phases during metamorphism. A model is presented that predicts the dispersion of elemental and isotopic ratios due to the nugget effect when the analyzed sample mass is limited and elements are concentrated in minor grains. The dispersion in REE patterns of equilibrated ordinary chondrites is reproduced well by this model, considering that REEs are concentrated in 200 μm-size phosphates, which have high LaN/LuN ratios and negative Eu anomalies. Terrestrial rocks and samples from ordinary and enstatite chondrites display negative Tm anomalies of ∼-4.5% relative to CI chondrites. In contrast, CM, CO and CV (except Allende) show no significant Tm anomalies. Allende CV chondrite shows large excess Tm (∼+10%). These anomalies are similar to those found in group II refractory inclusions in meteorites but of much smaller magnitude. The presence of Tm anomalies in meteorites and terrestrial rocks suggests that either (i) the material in the inner part of the solar system was formed from a gas reservoir that had been depleted in refractory dust and carried positive Tm anomalies or (ii) CI chondrites are enriched in refractory dust and are not representative of solar composition for

  7. Galactic cosmic rays - atmosphere clouds effect and bifurcation model of the Earth global climate

    NASA Astrophysics Data System (ADS)

    Glushkov, Alexander

    The possible physical linkage between the cosmic rays, atmosphere cloud and indirect aerosol effects is discussed using analysis of first indirect aerosol effect (Twomey effect) and its experimental representation as the dependence of mean cloud droplet effective radius versus aerosol index defining the column aerosol number. It is shown that the main kinetic equation of Earth climate energy-balance model [1] is described by the bifurcation equation (relative to the Earth surface temperature) in the form of fold catastrophe with two controlling parameters defining the variations of insolation and Earth magnetic field (or cosmic rays intensity in the atmosphere) respectively. The results of comparative analysis on the time-dependent solution (time series of global paleotemperature ) of Earth climate energy-balance model taking into account nontrivial role of galactic cosmic rays and the known experimental data on the palaeotemperature from the EPICA Dome C and Vostok ice core are pre-sented. It is discussed the sin-earth mechanism of arising the abnormal temperature breaks which are observed in the EPICA Dome C and Vostok experiments. It has been found its link with the ‘order-chaos' transitions in evolution of the convection in the Earth liquid core which are responsible for mechanism of arising inversions of the magnetic field of the Earth. It should be noted a stabilization role of the slow nuclear burning [1] georeactor with power 30 TW) on the boundary of the liquid and solid phases of the Earth's core in evolution of convection in the Earth liquid core and magnetic field. In the bifurcation model (i) the possibility of abrupt glacial climate changes analogous to the Dansgaard-Oeschger events due to stochastic resonance is theoretically argued, (ii) the concept of the climatic sensitivity of water (vapour and liquid) in the atmosphere is introduced. This concept reveals the property of temperature instability in a form of so-called hysteresis loop. It is

  8. Atmospheric Effect on Remote Sensing of the Earth's Surface

    NASA Technical Reports Server (NTRS)

    Fraser, R. S.; Kaufman, Y. J. (Principal Investigator)

    1985-01-01

    Radiative transfer theory (RT) for an atmosphere with a nonuniform surface is the basis for understanding and correcting for the atmospheric effect on remote sensing of surface properties. In the present work the theory is generalized and tested successfully against laboratory and field measurements. There is still a need to generalize the RT approximation for off-nadir directions and to take into account anisotropic reflectance at the surface. The reflectance at the surface. The adjacency effect results in a significant modification of spectral signatures of the surface, and therefore results in modification of classifications, of separability of field classes, and of spatial resolution. For example, the 30 m resolution of the Thematic Mapper is reduced to 100 m by a hazy atmosphere. The adjacency effect depends on several optical parameters of aerosols: optical thickness, depth of aerosol layer, scattering phase function, and absorption. Remote sensing in general depends on these parameter, not just adjacency effects, but they are not known well enough for making accurate atmospheric corrections. It is important to establish methods for estimating these parameters in order to develop correction methods for atmospheric effects. Such estimations can be based on climatological data, which are not available yet, correlations between the optical parameters and meteorological data, and the same satellite measurements of radiances that are used for estimating surface properties. Knowledge about the atmospheric parameters important for remote sensing is being enlarged with current measurements of them.

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

    SciTech Connect

    Eliav, U. E-mail: eliav@tau.ac.il; Haimovich, A.; Goldbourt, A. E-mail: eliav@tau.ac.il

    2016-01-14

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

  10. The effect of rare earth elements on the texture and formability of asymmetrically rolled magnesium sheet

    SciTech Connect

    Alderman, Dr. Martyn; Cavin, Odis Burl; Davis, Dr. Bruce; Muralidharan, Govindarajan; Muth, Thomas R; Peter, William H; Randman, David; Watkins, Thomas R

    2011-01-01

    The lack of formability is a serious issue when considering magnesium alloys for various applications. Standard symmetric rolling introduces a strong basal texture that decreases the formability; however, asymmetric rolling has been put forward as a possible route to produce sheet with weaker texture and greater ductility. It has also been shown in recent work that weaker textures can be produced through the addition of rare earth elements to magnesium alloys. Therefore, this study has been carried out to investigate the effect of rare earth additions on the texture changes during asymmetric rolling. Two alloys have been used, AZ31B and ZEK100. The effect that the rare earth additions have on the texture of asymmetrically rolled sheet and the subsequent changes in formability will be discussed.

  11. Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys.

    PubMed

    Alkahtani, Saleh A; Elgallad, Emad M; Tash, Mahmoud M; Samuel, Agnes M; Samuel, Fawzy H

    2016-01-13

    The present study was performed on A356 alloy [Al-7 wt %Si 0.0.35 wt %Mg]. To that La and Ce were added individually or combined up to 1.5 wt % each. The results show that these rare earth elements affect only the alloy melting temperature with no marked change in the temperature of Al-Si eutectic precipitation. Additionally, rare earth metals have no modification effect up to 1.5 wt %. In addition, La and Ce tend to react with Sr leading to modification degradation. In order to achieve noticeable modification of eutectic Si particles, the concentration of rare earth metals should exceed 1.5 wt %, which simultaneously results in the precipitation of a fairly large volume fraction of insoluble intermetallics. The precipitation of these complex intermetallics is expected to have a negative effect on the alloy performance.

  12. Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys

    PubMed Central

    Alkahtani, Saleh A.; Elgallad, Emad M.; Tash, Mahmoud M.; Samuel, Agnes M.; Samuel, Fawzy H.

    2016-01-01

    The present study was performed on A356 alloy [Al-7 wt %Si 0.0.35 wt %Mg]. To that La and Ce were added individually or combined up to 1.5 wt % each. The results show that these rare earth elements affect only the alloy melting temperature with no marked change in the temperature of Al-Si eutectic precipitation. Additionally, rare earth metals have no modification effect up to 1.5 wt %. In addition, La and Ce tend to react with Sr leading to modification degradation. In order to achieve noticeable modification of eutectic Si particles, the concentration of rare earth metals should exceed 1.5 wt %, which simultaneously results in the precipitation of a fairly large volume fraction of insoluble intermetallics. The precipitation of these complex intermetallics is expected to have a negative effect on the alloy performance. PMID:28787844

  13. Effects of dynamic long-period ocean tides on changes in earth's rotation rate

    NASA Technical Reports Server (NTRS)

    Nam, Young; Dickman, S. R.

    1990-01-01

    As a generalization of the zonal response coefficient first introduced by Agnew and Farrell (1978), the zonal response function kappa of the solid earth-ocean system is defined as the ratio, in the frequency domain, of the tidal change in earth's rotation rate to the tide-generating potential. Amplitudes and phases of kappa for the monthly, fortnightly, and nine-day lunar tides are estimated from 2 1/2 years of VLBI UT1 observations, corrected for atmospheric angular momentum effects using NMC wind and pressure series. Using the dynamic ocean tide model of Dickman (1988, 1989), amplitudes and phases of kappa for an elastic earth-ocean system are predicted. The predictions confirm earlier results which found that dynamic effects of the longer-period ocean tides reduce the amplitude of kappa by about 1 percent.

  14. Effects of dynamic long-period ocean tides on changes in earth's rotation rate

    NASA Technical Reports Server (NTRS)

    Nam, Young; Dickman, S. R.

    1990-01-01

    As a generalization of the zonal response coefficient first introduced by Agnew and Farrell (1978), the zonal response function kappa of the solid earth-ocean system is defined as the ratio, in the frequency domain, of the tidal change in earth's rotation rate to the tide-generating potential. Amplitudes and phases of kappa for the monthly, fortnightly, and nine-day lunar tides are estimated from 2 1/2 years of VLBI UT1 observations, corrected for atmospheric angular momentum effects using NMC wind and pressure series. Using the dynamic ocean tide model of Dickman (1988, 1989), amplitudes and phases of kappa for an elastic earth-ocean system are predicted. The predictions confirm earlier results which found that dynamic effects of the longer-period ocean tides reduce the amplitude of kappa by about 1 percent.

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

    PubMed

    Fechtelkord, M

    2000-01-01

    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.

  16. Two-photon absorption properties of proquinoidal D-A-D and A-D-A quadrupolar chromophores.

    PubMed

    Susumu, Kimihiro; Fisher, Jonathan A N; Zheng, Jieru; Beratan, David N; Yodh, Arjun G; Therien, Michael J

    2011-06-09

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

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

    PubMed Central

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    The uses of microcoils and WURST pulses for acquiring ultra-wideline (UW) NMR spectra of half-integer quadrupolar nuclei are explored. Using large rf field strengths or frequency-swept pulses, UW spectra (breadth > 300 kHz) can be acquired without changing the transmitter frequency. The efficiency of UWNMR spectroscopy improves for both microcoil and WURST pulse experiments compared to rectangular-pulse experiments using a 4.0 mm coil. Microcoils are also used to acquire UW spectra of an unreceptive nucleus ( 91Zr) and a spectrum comprised of both central and satellite transitions ( 59Co).

  19. Global single ion effects within the Earth's plasma sheet

    NASA Astrophysics Data System (ADS)

    Rothwell, Paul L.; Yates, G. Kenneth

    Two global properties of single ion motion in the magnetotail are examined. The first effect is caused by the magnetic field in the plasma sheet directing boundary ions to the neutral sheet. Exact solutions to the Lorentz equation indicate that these ions can have sufficient energy to trigger the ion tearing mode if Bo/aBz > 6.0, where Bo is the tail lobe magnetic field, Bz is the magnetic field in the north-south direction and `a' is a parameter related to the growth of the ion tearing instability. It is found that this effect occurs at a lower energy for oxygen than for protons. The second global property is related to the thinning or expansion of the plasma sheet. The results indicate that in the absence of reconnection the plasma sheet adiabatically maintains equilibruim by allowing plasma and magnetic flux to cross the boundaries. The presence of reconnection modifies the flow across the boundaries as well as the spatial distribution of the induced electric field.

  20. Global single ion effects within the earth's plasma sheet

    NASA Astrophysics Data System (ADS)

    Rothwell, P. L.; Yates, G. K.

    Two global properties of single-ion motion in the magnetotail are examined. The first effect is caused by the magnetic field in the plasma sheet directing boundary ions to the neutral sheet. Exact solutions to the Lorentz equation indicate that these ions can have sufficient energy to trigger the ion tearing mode if B0/aBz is greater than 6.0, where B0 is the tail-lobe magnetic field, Bz is the magnetic field in the north-south direction, and a is a parameter related to the growth of the ion tearing instability. It is found that this effect occurs at a lower energy for oxygen than for protons. The second global property is related to the thinning or expansion of the plasma sheet. In the absence of reconnection, the plasma sheet adiabatically maintains equilibrium by allowing plasma and magnetic flux to cross the boundaries. The presence of reconnection modifies the flow across the boundaries as well as the spatial distribution of the induced electric field.

  1. Imaging the earth's magnetosphere - Effects of plasma flow and temperature

    NASA Technical Reports Server (NTRS)

    Garrido, D. E.; Smith, R. W.; Swift, D. S.; Akasofu, S.-I.

    1991-01-01

    The effects of Doppler shifting on the line centers of the magnetospheric O(+) cross section are investigated, and the resulting structure of the scattering rate as a function of bulk density is explained. Whereas the Doppler shifting frequently results in a decrease of the scattering rate, it is demonstrated that for certain drift speeds the overlap of the cross section and the solar intensity profile can lead to an increased rate, thus enhancing the relative brightness of the image above that obtained when v(p) is zero. Simulated images of the magnetosphere are obtained which are used to show quantitively how the magnetospheric image responds to variations in plasma drift speed and temperature. Changes in the brightness of the magnetospheric images also depend on the variability of the solar flux at 83.4 nm. In regions where there are plasma drifts, the brightness in the image is governed by the structure of the scattering rate, assuming a fixed temperature.

  2. Low Earth Orbit Environmental Effects on Space Tether Materials

    NASA Technical Reports Server (NTRS)

    Finckernor, Miria M.; Gitlemeier, Keith A.; Hawk, Clark W.; Watts, Ed

    2005-01-01

    Atomic oxygen (AO) and ultraviolet (UV) radiation erode and embrittle most polymeric materials. This research was designed to test several different materials and coatings under consideration for their application to space tethers, for resistance to these effects. The samples were vacuum dehydrated, weighed and then exposed to various levels of AO or UV radiation at the NASA Marshall Space Flight Center. They were then re-weighed to determine mass loss due to atomic oxygen erosion, inspected for damage and tensile tested to determine strength loss. The experiments determined that the Photosil coating process, while affording some protection, damaged the tether materials worse than the AO exposure. TOR-LM also failed to fully protect the materials, especially from UV radiation. The POSS and nickel coatings did provide some protection to the tethers, which survived the entire test regime. M5 was tested, uncoated, and survived AO exposure, though its brittleness prevented any tensile testing.

  3. Relativistic effects of the rotation of the earth on remote clock synchronization

    NASA Technical Reports Server (NTRS)

    Reinhardt, V.

    1974-01-01

    A treatment is given of relativistic clock synchronization effects due to the rotation of the earth. Unlike other approaches, the point of view of an earth fixed coordinate system is used which offers insight to many problems. An attempt is made to give the reader an intuitive grasp of the subject as well as to provide formulae for his use. Specific applications to global timekeeping, navigation, VLBI, relativistic clock experiments, and satellite clock synchronization are discussed. The question of whether atomic clocks are ideal clocks is also treated.

  4. Removal of earth's magnetic field effect on magnetoelastic resonance sensors by an antisymmetric bias field.

    PubMed

    Bergmair, Bernhard; Huber, Thomas; Bruckner, Florian; Vogler, Christoph; Suess, Dieter

    2012-08-01

    Magnetoelastic sensors are used in a wide field of wireless sensing applications. The sensing element is a low-cost magnetostrictive ribbon whose resonant frequency depends on the measured quantity. The accuracy of magnetoelastic sensors is limited by the fact that the resonant frequency is also affected by the earth's magnetic field. In this paper we present a technique to minimize this effect by applying an antisymmetric magnetic bias field to the ribbon. The ribbon's response to external perturbation fields was measured and compared to a conventional sensor design. Our results show that the influence of the earth's magnetic field could be reduced by 77%.

  5. The Effects of an Earth Science Curriculum Revision on Teacher Behavior and Student Achievement. Final Report.

    ERIC Educational Resources Information Center

    Orgren, James R.

    A two-year study on the effects of adopting the 1970 revision of the New York State Regents Earth Science Syllabus on teachers' teaching strategies and educational opinions and students' abilities and performance was reported. A total of about 30 teachers and their classrooms were used. One group used the old syllabus in the first year and the new…

  6. Effects of dynamic long-period ocean tides on changes in Earth's rotation rate

    SciTech Connect

    Nam, Y.S.; Dickman, S.R. )

    1990-05-10

    As a generalization of the zonal response coefficient first introduced by Agnew and Farrell (1978), the authors define the zonal response function k of the solid earth-ocean system as the ratio, in the frequency domain, of the tidal change in Earth's rotation rate to the tide-generating potential. Amplitudes and phases of k for the monthly, fortnightly, and 9-day lunar tides are estimated from 2 1/2 years of very long baseline interferometry UTI observations (both 5-day and daily time series), corrected for atmospheric angular momentum effects using NMC wind and pressure series. Using the dynamic ocean tide model of Dickman (1988a, 1989a), the authors predict amplitudes and phases of k for an elastic earth-ocean system. The predictions confirm earlier results which found that dynamic effects of the longer-period ocean tides reduce the amplitude of k by about 1%. However, agreement with the observed k is best achieved for all three tides if the predicted tide amplitudes are combined with the much larger satellite-observed ocean tide phases; in these cases the dynamic tidal effects reduce k by up to 8%. Finally, comparison between the observed and predicted amplitudes of k implies that anelastic effects on Earth's rotation at periods less than fortnightly cannot exceed 2%.

  7. The effects of solar Reimers η on the final destinies of Venus, the Earth, and Mars

    NASA Astrophysics Data System (ADS)

    Guo, Jianpo; Lin, Ling; Bai, Chunyan; Liu, Jinzhong

    2016-04-01

    Our Sun will lose sizable mass and expand enormously when it evolves to the red giant branch phase and the asymptotic giant branch phase. The loss of solar mass will push a planet outward. On the contrary, solar expansion will enhance tidal effects, and tidal force will drive a planet inward. Will our Sun finally engulf Venus, the Earth, and Mars? In the literature, one can find a large number of studies with different points of view. A key factor is that we do not know how much mass the Sun will lose at the late stages. The Reimers η can describe the efficiency of stellar mass-loss and greatly affect solar mass and solar radius at the late stages. In this work, we study how the final destinies of Venus, the Earth, and Mars can be depending on Reimers η chosen. In our calculation, the Reimers η varies from 0.00 to 0.75, with the minimum interval 0.0025. Our results show that Venus will be engulfed by the Sun and Mars will most probably survive finally. The fate of the Earth is uncertain. The Earth will finally be engulfed by the Sun while η <0.4600, and it will finally survive while η ≥ 0.4600. New observations indicate that the average Reimers η for solar-like stars is 0.477. This implies that Earth may survive finally.

  8. Crystal-field interaction and oxygen stoichiometry effects in strontium-doped rare-earth cobaltates

    NASA Astrophysics Data System (ADS)

    Furrer, A.; Podlesnyak, A.; Frontzek, M.; Sashin, I.; Embs, J. P.; Mitberg, E.; Pomjakushina, E.

    2014-08-01

    Inelastic neutron scattering was employed to study the crystal-field interaction in the strontium-doped rare-earth compounds RxSr1-xCoO3-z (R=Pr, Nd, Ho, and Er). Particular emphasis is laid on the effect of oxygen deficiencies that naturally occur in the synthesis of these compounds. The observed energy spectra are found to be the result of a superposition of crystal fields with different nearest-neighbor oxygen coordination at the R sites. The experimental data are interpreted in terms of crystal-field parameters, which behave in a consistent manner through the rare-earth series, thereby allowing a reliable extrapolation for rare-earth ions not considered in the present work.

  9. The Study of Effects of Time Variations in the Earth's Gravity Field on Geodetic Satellites

    NASA Technical Reports Server (NTRS)

    Shum, C. K.

    1998-01-01

    The temporal variations in the Earth's gravity field are the consequences of complex interactions between atmosphere, ocean, solid Earth, hydrosphere and cryosphere. The signal ranges from several hours to 18.6 years to geological time scale. The direct and indirect consequences of these variations are manifested in such phenomena as changes in the global sea level and in the global climate pattern. These signals produce observable geodetic satellites. The primary objectives of the proposed effects on near-Earth orbiting investigation include (1) the improved determination of the time-varying gravity field parameters (scale from a few hour to 18.6 year and secular) using long-term satellite laser rs ranging (SLR) observations to multiple geodetic satellites, and (2) the enhanced understanding of these variations with their associated meteorological and geophysical consequences.

  10. Spatial nonlinearities: Cascading effects in the earth system

    USGS Publications Warehouse

    Peters, Debra P.C.; Pielke, R.A.; Bestelmeyer, B.T.; Allen, Craig D.; Munson-McGee, S.; Havstad, K. M.

    2006-01-01

    Nonlinear interactions and feedbacks associated with thresholds through time and across space are common features of biological, physical and materials systems. These spatial nonlinearities generate surprising behavior where dynamics at one scale cannot be easily predicted based on information obtained at finer or broader scales. These cascading effects often result in severe consequences for the environment and human welfare (i.e., catastrophes) that are expected to be particularly important under conditions of changes in climate and land use. In this chapter, we illustrate the usefulness of a general conceptual and mathematical framework for understanding and forecasting spatially nonlinear responses to global change. This framework includes cross-scale interactions, threshold behavior and feedback mechanisms. We focus on spatial nonlinearities produced by fine-scale processes that cascade through time and across space to influence broad spatial extents. Here we describe the spread of catastrophic events in the context of our cross-disciplinary framework using examples from biology (wildfires, desertification, infectious diseases) and engineering (structural failures) and discuss the consequences of applying these ideas to forecasting future dynamics under a changing global environment.

  11. 5f delocalization-induced suppression of quadrupolar order in U(Pd1-xPtx)₃

    SciTech Connect

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

    2011-12-27

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

  12. The Effect of Rare Earth Dopants on UO2 Oxidation

    SciTech Connect

    Hanson, Brady D.; Cumblidge, Stephen E.; Scheele, Randall D.; Sell, Rachel L.

    2003-06-01

    Recent work by Hanson [1] has demonstrated a clear dependence of the oxidation of Light Water Reactor spent fuel on burnup. Oxidation of spent fuel was shown to proceed via the two-step reaction UO2?UO2.4?UO2.67+x, where the U3O8-like phase does not form until conversion to UO2.4 is complete. The temperature-dependent activation energy (Ea) of the transition from UO2.4 to the hyperstoichiometric U3O8 was found to be {approx}150 kJ mol-1. Each MWD/kg M burnup added {approx}1.0 kJ mol-1. The work of McEachern et.al. [2], Choi et. al. [3], and You et. al. [4] have all verified this oxidation dependence on SIMFUEL or unirradiated doped-UO2. All present work agrees that the soluble actinides or fission products that substitute in the U matrix act to delay the onset of U3O8. However, no single model exists to explain the observed behavior, including the fact that most dopants actually allow an earlier onset for UO2.4 formation. The present work is part of a Nuclear Energy Research Initiative project attempting to develop a UO2-based matrix capable of achieving extended burnups by including soluble dopants. The resulting fuel should be highly oxidation and dissolution resistant, which will be beneficial during accident scenarios or for disposal in a geologic repository. In addition, the stabilized matrix may help delay the onset of fuel restructuring that occurs at higher burnups. Initial results of the oxidation tests to quantify effects as a function of ionic radii and charge of the dopant are presented.

  13. Effects of dimensionality in the rare-earth manganates

    SciTech Connect

    Gundakaram, R.; Huang, C.Y.

    1999-12-20

    The authors report measurements of magnetization, magnetoresistance and ESR on systems with the 3-D and layered structures, to study the effect of reduced dimensionality. Compositions of the systems Pr{sub 0.7}Sr{sub 0.3{minus}x}Ca{sub x}MnO{sub 3} and La{sub 2{minus}2y}Sr{sub 1+2y}Mn{sub 2{minus}z}Cr{sub z}O{sub 7} were synthesized, which have the 3D and quasi-2D structures, respectively. The magnetic and transport properties are markedly affected by the reduction in dimensionality. Large values of magnetoresistance have been observed in the layered materials even at low temperature, in contrast with the behavior of the 3D compositions. ESR measurements on the Pr{sub 0.7}Sr{sub 0.3{minus}x}Ca{sub x}MnO{sub 3} system show a single resonance line in the temperature range of the study. However, compositions of the La{sub 2{minus}2y}Sr{sub 1+2y}Mn{sub 2}O{sub 7} system with y = 0.3, 0.4 and 0.5 show a complex behavior. As the samples are cooled, a single resonance line is first observed, which can be described by a Lorentzian. Below {approximately}2{Tc}, for compositions with y = 0.3 and 0.4, a complex lineshape evolves, which can be resolved into two Gaussian lines. This crossover in the lineshape indicates a transition from a homogeneous to an inhomogeneous spin system, which can be attributed to the nature of the ferromagnetic ordering between the bilayers. The composition with y = 0.5 shows a different behavior, which might be due to the antiferromagnetic ordering exhibited by this composition. A detailed analysis of the experiments is presented.

  14. Earth matter effects on supernova neutrinos in large-volume detectors

    NASA Astrophysics Data System (ADS)

    Borriello, Enrico

    2013-04-01

    Neutrino oscillations in the Earth matter may introduce peculiar modulations in the supernova (SN) neutrino spectra. The detection of this effect has been proposed as diagnostic tool for the neutrino mass hierarchy. We perform an updated study on the observability of this effect at large next-generation underground detectors (i.e., 0.4 Mton water Cherenkov, 50 kton scintillation and 100 kton liquid Argon detectors) based on neutrino fluxes from state-of-the-art SN simulations and accounting for statistical fluctuations via Montecarlo simulations. Since the average energies predicted by recent simulations are lower than previously expected and a tendency towards the equalization of the neutrino fluxes appears during the SN cooling phase, the detection of the Earth matter effect will be more challenging than expected from previous studies. We find that none of the proposed detectors shall be able to detect the Earth modulation for the neutrino signal of a typical galactic SN at 10 kpc. It should be observable in a 100 kton liquid Argon detector for a SN at few kpc and all three detectors would clearly see the Earth signature for very close-by stars only (d˜200 pc).

  15. The Effect of the Earth's and Stray Magnetic Fields on Mobile Mass Spectrometer Systems

    NASA Astrophysics Data System (ADS)

    Bell, Ryan J.; Davey, Nicholas G.; Martinsen, Morten; Short, R. Timothy; Gill, Chris G.; Krogh, Erik T.

    2015-02-01

    Development of small, field-portable mass spectrometers has enabled a rapid growth of in-field measurements on mobile platforms. In such in-field measurements, unexpected signal variability has been observed by the authors in portable ion traps with internal electron ionization. The orientation of magnetic fields (such as the Earth's) relative to the ionization electron beam trajectory can significantly alter the electron flux into a quadrupole ion trap, resulting in significant changes in the instrumental sensitivity. Instrument simulations and experiments were performed relative to the earth's magnetic field to assess the importance of (1) nonpoint-source electron sources, (2) vertical versus horizontal electron beam orientation, and (3) secondary magnetic fields created by the instrument itself. Electron lens focus effects were explored by additional simulations, and were paralleled by experiments performed with a mass spectrometer mounted on a rotating platform. Additionally, magnetically permeable metals were used to shield (1) the entire instrument from the Earth's magnetic field, and (2) the electron beam from both the Earth's and instrument's magnetic fields. Both simulation and experimental results suggest the predominant influence on directionally dependent signal variability is the result of the summation of two magnetic vectors. As such, the most effective method for reducing this effect is the shielding of the electron beam from both magnetic vectors, thus improving electron beam alignment and removing any directional dependency. The improved ionizing electron beam alignment also allows for significant improvements in overall instrument sensitivity.

  16. The effect of the earth's and stray magnetic fields on mobile mass spectrometer systems.

    PubMed

    Bell, Ryan J; Davey, Nicholas G; Martinsen, Morten; Short, R Timothy; Gill, Chris G; Krogh, Erik T

    2015-02-01

    Development of small, field-portable mass spectrometers has enabled a rapid growth of in-field measurements on mobile platforms. In such in-field measurements, unexpected signal variability has been observed by the authors in portable ion traps with internal electron ionization. The orientation of magnetic fields (such as the Earth's) relative to the ionization electron beam trajectory can significantly alter the electron flux into a quadrupole ion trap, resulting in significant changes in the instrumental sensitivity. Instrument simulations and experiments were performed relative to the earth's magnetic field to assess the importance of (1) nonpoint-source electron sources, (2) vertical versus horizontal electron beam orientation, and (3) secondary magnetic fields created by the instrument itself. Electron lens focus effects were explored by additional simulations, and were paralleled by experiments performed with a mass spectrometer mounted on a rotating platform. Additionally, magnetically permeable metals were used to shield (1) the entire instrument from the Earth's magnetic field, and (2) the electron beam from both the Earth's and instrument's magnetic fields. Both simulation and experimental results suggest the predominant influence on directionally dependent signal variability is the result of the summation of two magnetic vectors. As such, the most effective method for reducing this effect is the shielding of the electron beam from both magnetic vectors, thus improving electron beam alignment and removing any directional dependency. The improved ionizing electron beam alignment also allows for significant improvements in overall instrument sensitivity.

  17. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction.

    PubMed

    Cramer, Alisha J; Cole, Jacqueline M; FitzGerald, Vicky; Honkimaki, Veijo; Roberts, Mark A; Brennan, Tessa; Martin, Richard A; Saunders, George A; Newport, Robert J

    2013-06-14

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3)x(R'2O3)y(P2O5)(1-(x+y)), where (R, R') denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP5O14. Thereupon, the effects of rare-earth co-doping on the local structure are assessed at the atomic level. Pair-distribution function analysis of high-energy X-ray diffraction data (Q(max) = 28 Å(-1)) is employed to make this assessment. Results reveal a stark structural invariance to rare-earth co-doping which bears testament to the open-framework and rigid nature of these glasses. A range of desirable attributes of these glasses unfold from this finding; in particular, a structural simplicity that will enable facile molecular engineering of rare-earth phosphate glasses with 'dial-up' lasing properties. When considered together with other factors, this finding also demonstrates additional prospects for these co-doped rare-earth phosphate glasses in nuclear waste storage applications. This study also reveals, for the first time, the ability to distinguish between P-O and P[double bond, length as m-dash]O bonding in these rare-earth phosphate glasses from X-ray diffraction data in a fully quantitative manner. Complementary analysis of high-energy X-ray diffraction data on single rare-earth phosphate glasses of similar rare-earth composition to the co-doped materials is also presented in this context. In a technical sense, all high-energy X-ray diffraction data on these glasses are compared with analogous low-energy diffraction data; their salient differences reveal distinct advantages of high-energy X-ray diffraction data for the study of amorphous materials.

  18. The association of coronal mass ejections with their effects near the Earth

    NASA Astrophysics Data System (ADS)

    Schwenn, R.; dal Lago, A.; Huttunen, E.; Gonzalez, W. D.

    2005-03-01

    To this day, the prediction of space weather effects near the Earth suffers from a fundamental problem: The radial propagation speed of "halo" CMEs (i.e. CMEs pointed along the Sun-Earth-line that are known to be the main drivers of space weather disturbances) towards the Earth cannot be measured directly because of the unfavorable geometry. From inspecting many limb CMEs observed by the LASCO coronagraphs on SOHO we found that there is usually a good correlation between the radial speed and the lateral expansion speed Vexp of CME clouds. This latter quantity can also be determined for earthward-pointed halo CMEs. Thus, Vexp may serve as a proxy for the otherwise inaccessible radial speed of halo CMEs. We studied this connection using data from both ends: solar data and interplanetary data obtained near the Earth, for a period from January 1997 to 15 April 2001. The data were primarily provided by the LASCO coronagraphs, plus additional information from the EIT instrument on SOHO. Solar wind data from the plasma instruments on the SOHO, ACE and Wind spacecraft were used to identify the arrivals of ICME signatures. Here, we use "ICME" as a generic term for all CME effects in interplanetary space, thus comprising not only ejecta themselves but also shocks as well. Among 181 front side or limb full or partial halo CMEs recorded by LASCO, on the one hand, and 187 ICME events registered near the Earth, on the other hand, we found 91 cases where CMEs were uniquely associated with ICME signatures in front of the Earth. Eighty ICMEs were associated with a shock, and for 75 of them both the halo expansion speed Vexp and the travel time Ttr of the shock could be determined. The function Ttr=203-20.77*ln (Vexp fits the data best. This empirical formula can be used for predicting further ICME arrivals, with a 95% error margin of about one day. Note, though, that in 15% of comparable cases, a full or partial halo CME does not cause any ICME signature at Earth at all; every

  19. New Models of Water Delivery To Earth: The Effects of Ice Longevity and Collisional Water Transport

    NASA Astrophysics Data System (ADS)

    Maindl, Thomas I.; Haghighipour, Nader

    2016-10-01

    It is widely accepted that the vast majority of Earth's water was delivered to its accretion zone by water-carrying planetesimals and planetary embryos from the outer regions of the asteroid belt while Earth was still forming. Modern simulations of the formation of terrestrial planets show this process with high resolution. However, their treatment of the actual delivery of water is still rudimentary assuming that a water-carrying object will maintain all its water content during its journey from its original orbit to the accretion zone of Earth. Models of the ice longevity have, however, shown that the water-ice may not stay intact, and asteroids and planetary embryos may lose some of their original water in form of ice sublimation during the dynamical evolution of these bodies. Also, collisions among these bodies while on their journey to Earth's accretion zone will result in the loss of large amounts of their water. These effects could be especially important during the formation of terrestrial planets as this process takes tens to hundreds of millions of years. We have developed a more accurate model in which the sublimation of ice during the process of the scattering of icy asteroids and planetary embryos into the accretion zone of Earth is taken into account. Our model includes two different modes of handling ice sublimation, one for sub-surface water and one for deeper ice. We also estimate water loss and retention during collisions which depends on the physical and dynamical parameters of the impacts. The results of our simulations put stringent constraints on the initial water distribution in the protoplanetary disk, the location of snowline, and the contribution of water from the primordial nebula to the final water budget of Earth. In this poster, we will present the results of our new simulations and discuss their implications for models of solar system formation and dynamics.

  20. Ultrahigh-field NMR spectroscopy of quadrupolar transition metals: 55Mn NMR of several solid manganese carbonyls.

    PubMed

    Ooms, Kristopher J; Feindel, Kirk W; Terskikh, Victor V; Wasylishen, Roderick E

    2006-10-16

    55Mn NMR spectra acquired at 21.14 T (nu(L)(55Mn) = 223.1 MHz) are presented and demonstrate the advantages of using ultrahigh magnetic fields for characterizing the chemical shift tensors of several manganese carbonyls: eta5-CpMn(CO)3, Mn2(CO)10, and (CO)5MnMPh3 (M = Ge, Sn, Pb). For the compounds investigated, the anisotropies of the manganese chemical shift tensors are less than 250 ppm except for eta5-CpMn(CO)3, which has an anisotropy of 920 ppm. At 21.14 T, one can excite the entire m(I) = 1/2 <--> m(I) = -1/2 central transition of eta5-CpMn(CO)3, which has a breadth of approximately 700 kHz. The breadth arises from second-order quadrupolar broadening due to the 55Mn quadrupolar coupling constant of 64.3 MHz, as well as the anisotropic shielding. Subtle variations in the electric field gradient tensors at the manganese are observed for crystallographically unique sites in two of the solid pentacarbonyls, resulting in measurably different C(Q) values. MQMAS experiments are able to distinguish four magnetically unique Mn sites in (CO)(5)MnPbPh3, each with slightly different values of delta(iso), C(Q), and eta(Q).

  1. Integrated Computational Protocol for Analyzing Quadrupolar Splittings from Natural Abundance Deuterium NMR Spectra in (Chiral) Oriented Media.

    PubMed

    Navarro-Vazquez, Armando; Berdagué, Philippe; Lesot, Philippe Georges Julien

    2017-03-03

    Despite its low natural abundance, deuterium NMR in weakly oriented (chiral) solvents gives easy access to deuterium residual quadrupolar couplings (2H-RQCs), which are formally equivalent to one-bond 1DCH (13C-1H)-RDCs for calculation of the Saupe order matrix, furnishing similar information to study molecular structure and orientational behavior. In addition, the quadrupolar interaction is one order of magnitude larger than the dipolar interaction, making 2H-RQC analysis much more sensitive tool for structural analysis. Subtle structural differences as well as tiny differences in the molecular alignment of different enantiomers in chiral aligning media can be detected. In order to promote this approach towards organic chemists interested in exploiting the analytical advantages of anisotropic, natural abundance deuterium NMR (NAD NMR), we describe a 2H-RQC/DFT-based integrated computational protocol for the evaluation of the order parameters of aligned solutes via singular value decomposition. Examples of 2H-RQC-assisted analysis of chiral and prochiral molecules dissolved in various polypeptide lyotropic chiral liquid crystals are reported. They illustrate the power of this hyphenated approach and in particular to understand the alignment processes and the role of molecular shape in the ordering mechanism through the determination of inter-tensor angles between alignment tensors and inertia tensors.

  2. The interplay of the crystalline electric field and quadrupolar interactions in the spontaneous magnetic phases of DyIn3

    NASA Astrophysics Data System (ADS)

    Galéra, R. M.; Sole, E.; Amara, M.; Morin, P.; Burlet, P.; Murani, A. P.

    2003-09-01

    DyIn3 orders at TN = 20 K and undergoes a second spontaneous magnetic transition at 16.5 K. From bulk magnetization measurements, performed on a single crystal along the three main axes of the cubic AuCu3-type structure, the magnetic phase diagrams have been established. The crystalline electric field (CEF) scheme, in the paramagnetic phase, and the magnetic structures of the spontaneous and low field-induced phases have been probed by neutron techniques. All the magnetic phases studied are found to be multiple q with q belonging to the langle1/2, 1/2, 0rangle star. In the low temperature phase (T < 16.5 K) the structure is double q with moments along twofold axes, whereas above 16.5 K it becomes triple q with moments along threefold axes. The analysis of the experimental results within the periodic molecular field model leads to a coherent interpretation of the spontaneous magnetic transitions, mainly driven by bilinear exchange and CEF interactions. Though the existence of quadrupolar interactions is definitively proved by the stabilization of multiple q magnetic structures, quadrupolar coefficients are found to be one order of magnitude smaller than those previously reported for NdIn3 and TbIn3.

  3. Antiferroquadrupolar Ordering in Quadrupolar Kondo Lattice of Non-Kramers System PrTa2Al20

    NASA Astrophysics Data System (ADS)

    Higashinaka, Ryuji; Nakama, Akihiro; Miyazaki, Ryoichi; Yamaura, Jun-ichi; Sato, Hideyuki; Aoki, Yuji

    2017-10-01

    Single crystals of PrTa2Al20 have been investigated by means of single-crystal structural analysis and measurements of magnetization, specific heat, and electrical resistivity. The crystalline-electric-field level scheme of the Pr ions has a nonmagnetic Γ3 doublet ground state and a Γ5 magnetic excited state with an energy separation of 53 K. The 4f-electron contribution to the electrical resistivity shows -log T magnetic Kondo scattering above 50 K and a downward curvature characteristic of a quadrupolar Kondo lattice formation below 20 K. A phase transition appears at 0.65 K in zero field and shifts to higher temperatures in applied fields, indicating that this transition is antiferroquadrupolar (AFQ) in nature. The largely enhanced Sommerfeld coefficient ˜1.5 J/(mol K2) in the AFQ state may indicate the formation of heavy quasiparticles. The hierarchically arranged sequence of the magnetic Kondo regime, quadrupolar Kondo lattice regime, and AFQ ordered state in the wide temperature range 0.2-300 K demonstrates that PrTa2Al20 is a good playground to investigate quadrupole physics with strong electron correlations.

  4. Effect of Oxygen Enrichment in Propane Laminar Diffusion Flames under Microgravity and Earth Gravity Conditions

    NASA Astrophysics Data System (ADS)

    Bhatia, Pramod; Singh, Ravinder

    2017-06-01

    Diffusion flames are the most common type of flame which we see in our daily life such as candle flame and match-stick flame. Also, they are the most used flames in practical combustion system such as industrial burner (coal fired, gas fired or oil fired), diesel engines, gas turbines, and solid fuel rockets. In the present study, steady-state global chemistry calculations for 24 different flames were performed using an axisymmetric computational fluid dynamics code (UNICORN). Computation involved simulations of inverse and normal diffusion flames of propane in earth and microgravity condition with varying oxidizer compositions (21, 30, 50, 100 % O2, by mole, in N2). 2 cases were compared with the experimental result for validating the computational model. These flames were stabilized on a 5.5 mm diameter burner with 10 mm of burner length. The effect of oxygen enrichment and variation in gravity (earth gravity and microgravity) on shape and size of diffusion flames, flame temperature, flame velocity have been studied from the computational result obtained. Oxygen enrichment resulted in significant increase in flame temperature for both types of diffusion flames. Also, oxygen enrichment and gravity variation have significant effect on the flame configuration of normal diffusion flames in comparison with inverse diffusion flames. Microgravity normal diffusion flames are spherical in shape and much wider in comparison to earth gravity normal diffusion flames. In inverse diffusion flames, microgravity flames were wider than earth gravity flames. However, microgravity inverse flames were not spherical in shape.

  5. Effect of Oxygen Enrichment in Propane Laminar Diffusion Flames under Microgravity and Earth Gravity Conditions

    NASA Astrophysics Data System (ADS)

    Bhatia, Pramod; Singh, Ravinder

    2017-01-01

    Diffusion flames are the most common type of flame which we see in our daily life such as candle flame and match-stick flame. Also, they are the most used flames in practical combustion system such as industrial burner (coal fired, gas fired or oil fired), diesel engines, gas turbines, and solid fuel rockets. In the present study, steady-state global chemistry calculations for 24 different flames were performed using an axisymmetric computational fluid dynamics code (UNICORN). Computation involved simulations of inverse and normal diffusion flames of propane in earth and microgravity condition with varying oxidizer compositions (21, 30, 50, 100 % O2, by mole, in N2). 2 cases were compared with the experimental result for validating the computational model. These flames were stabilized on a 5.5 mm diameter burner with 10 mm of burner length. The effect of oxygen enrichment and variation in gravity (earth gravity and microgravity) on shape and size of diffusion flames, flame temperature, flame velocity have been studied from the computational result obtained. Oxygen enrichment resulted in significant increase in flame temperature for both types of diffusion flames. Also, oxygen enrichment and gravity variation have significant effect on the flame configuration of normal diffusion flames in comparison with inverse diffusion flames. Microgravity normal diffusion flames are spherical in shape and much wider in comparison to earth gravity normal diffusion flames. In inverse diffusion flames, microgravity flames were wider than earth gravity flames. However, microgravity inverse flames were not spherical in shape.

  6. [Effects of arbuscular mycorrhizal fungi on the growth and rare earth elements uptake of soybean grown in rare earth mine tailings].

    PubMed

    Guo, Wei; Zhao, Ren-xin; Zhao, Wen-jing; Fu, Rui-ying; Guo, Jiang-yuan; Zhang, Jun

    2013-05-01

    A greenhouse pot experiment was conducted to investigate the influence of arbuscular mycorrhizal (AM) fungi Glomus versiforme on the plant growth, nutrient uptake, C: N: P stoichiometric, uptake of heavy metals and rare earth elements by soybean (Glycine max) grown in rare earth mine tailings. The aim was to provide a basis for the revegetation of rare earth mine tailings. The results indicated that soybean had a high mycorrhizal colonization and symbiotic associations were successfully established with G. versiforme, with an average rate of approximately 67%. The colonization of G. versiforme significantly promoted the growth of soybean, increased P, K contents, and decreased C: N: P ratios, supporting the growth rate hypothesis. Inoculation with G. versiforme significantly decreased shoots and roots La, Ce, Pr and Nd concentrations of soybean compared to the control treatment. However, inoculation with G. versiforme had no significant effect on the heavy metal concentrations, except for significantly decreased shoot Fe and Cr concentrations and increased root Cd concentrations. The experiment demonstrates that AM fungi have a potential role for soybean to adapt the composite adversity of rare earth tailings and play a positive role in revegetation of rare earth mine tailings. Further studies on the role of AM fungi under natural conditions should be conducted.

  7. Precambrian climate: The effects of land area and earth's rotation rate

    SciTech Connect

    Jenkins, G.S. ); Marshall, H.G.; Kuhn, W.R. )

    1993-05-20

    The authors present results of model studies using general circulation models of climatic effects of variations in the rotation rate of the earth. These studies are of relevance for the Precambrian times, when the rotation period of the earth was considerably shorter. The authors include in their model studies a number of factors which were left out in previous studies. The rotation rate has a strong effect on atmospheric circulation, as evidenced in the theory of geostrophic turbulence, mid-latitude baroclinic instability, and the Hadley cell. One can expect the contraction of circulation patterns, both horizontally and vertically. This should also impact heat transport, though questions of mean temperature effects are more open, unless one allows cloud cover to vary. The authors put more realistic starting conditions into the model, and also allow clouds and hydrology to have a feedback role to see what impact rotation rates will have on global climate.

  8. Low earth orbit environmental effects on the Space Station photovoltaic power generation systems

    NASA Technical Reports Server (NTRS)

    Nahra, H. K.

    1988-01-01

    A summary of the low earth orbital environment, its impact on the photovoltaic power systems of the Space Station and the solutions implemented to resolve the environmental concerns or issues are described. Low earth orbital environment (LEO) presents several concerns to the photovoltaic power systems of the Space Station. These concerns include atomic oxygen interaction with the polymeric substrate of the solar arrays, ionized environment effects on the array operating voltage, the effects of the meteoroids and debris impacts and penetration through the different layers of the solar cells and their circuits, and the high energy particle and radiation effects on the overall solar array performance. Potential solutions to some of the degrading environmental interactions that will provide the photovoltaic power system of the Space Station with the desired life are also summarized.

  9. Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

    SciTech Connect

    Ueda, Kohei; Pai, Chi-Feng; Tan, Aik Jun; Mann, Maxwell; Beach, Geoffrey S. D.

    2016-06-06

    We report the effect of the rare earth metal Gd on current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Pt/Co/Gd heterostructures, characterized using harmonic measurements and spin-torque ferromagnetic resonance (ST-FMR). By varying the Gd metal layer thickness from 0 nm to 8 nm, harmonic measurements reveal a significant enhancement of the effective fields generated from the Slonczewski-like and field-like torques. ST-FMR measurements confirm an enhanced effective spin Hall angle and show a corresponding increase in the magnetic damping constant with increasing Gd thickness. These results suggest that Gd plays an active role in generating SOTs in these heterostructures. Our finding may lead to spin-orbitronics device application such as non-volatile magnetic random access memory, based on rare earth metals.

  10. Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

    NASA Astrophysics Data System (ADS)

    Ueda, Kohei; Pai, Chi-Feng; Tan, Aik Jun; Mann, Maxwell; Beach, Geoffrey S. D.

    2016-06-01

    We report the effect of the rare earth metal Gd on current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Pt/Co/Gd heterostructures, characterized using harmonic measurements and spin-torque ferromagnetic resonance (ST-FMR). By varying the Gd metal layer thickness from 0 nm to 8 nm, harmonic measurements reveal a significant enhancement of the effective fields generated from the Slonczewski-like and field-like torques. ST-FMR measurements confirm an enhanced effective spin Hall angle and show a corresponding increase in the magnetic damping constant with increasing Gd thickness. These results suggest that Gd plays an active role in generating SOTs in these heterostructures. Our finding may lead to spin-orbitronics device application such as non-volatile magnetic random access memory, based on rare earth metals.

  11. Low Earth orbit environmental effects on the space station photovoltaic power generation systems

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.

    1987-01-01

    A summary of the Low Earth Orbital Environment, its impact on the Photovoltaic Power systems of the space station and the solutions implemented to resolve the environmental concerns or issues are described. Low Earth Orbital Environment (LEO) presents several concerns to the Photovoltaic power systems of the space station. These concerns include atomic oxygen interaction with the polymeric substrate of the solar arrays, ionized environment effects on the array operating voltage, the effects of the meteoroids and debris impacts and penetration through the different layers of the solar cells and their circuits, and the high energy particle and radiation effects on the overall solar array performance. Potential solutions to some of the degrading environmental interactions that will provide the photovoltaic power system of the space station with the desired life are also summarized.

  12. Effect of earth albedo variation on the performance of a spatial acquisition subsystem aboard a planetary spacecraft

    NASA Technical Reports Server (NTRS)

    Chen, C.-C.

    1988-01-01

    The effect of Earth albedo variation on the pointing and tracking subsystem of a planetary optical communication package is analyzed. By studying the Cramer-Rao bound of the tracking error variance, it is shown that, when the Earth albedo is precisely known, the variance in spatial tracking error is inversely proportional to the total signal count. In contrast, a small uncertainty in the Earth albedo can result in an irreducible error in the tracking subsystem.

  13. Earth Science

    NASA Image and Video Library

    1992-07-18

    Workers at Launch Complex 17 Pad A, Kennedy Space Center (KSC) encapsulate the Geomagnetic Tail (GEOTAIL) spacecraft (upper) and attached payload Assist Module-D upper stage (lower) in the protective payload fairing. GEOTAIL project was designed to study the effects of Earth's magnetic field. The solar wind draws the Earth's magnetic field into a long tail on the night side of the Earth and stores energy in the stretched field lines of the magnetotail. During active periods, the tail couples with the near-Earth magnetosphere, sometimes releasing energy stored in the tail and activating auroras in the polar ionosphere. GEOTAIL measures the flow of energy and its transformation in the magnetotail and will help clarify the mechanisms that control the imput, transport, storage, release, and conversion of mass, momentum, and energy in the magnetotail.

  14. What Is the Atmosphere’s Effect on Earth's Surface Temperature?

    NASA Astrophysics Data System (ADS)

    Zeng, Xubin

    2010-04-01

    It is frequently stated in textbooks and scholarly articles that the surface temperature of Earth is 33°C warmer than it would be without the atmosphere and that this difference is due to the greenhouse effect. This Forum shows that the atmosphere effect leads to warming of only 20°C. This new conclusion requires a revision to all of the relevant literature in K-12, undergraduate, and graduate education material and to science papers and reports. The greenhouse effect on Earth's surface temperature is well understood qualitatively and is regarded as basic knowledge about Earth's climate and climate change. The 33°C warming has been used to quantify the greenhouse effect of greenhouse gases, or of greenhouse gases and clouds, in K-12 educational material (e.g., http://epa.gov/climatechange/kids/greenhouse.html), undergraduate freshman introductory textbooks on weather and climate [e.g., Ahrens, 2008], and graduate textbooks on climate [e.g., Peixoto and Oort, 1992]. Some textbooks and various other publications have less stringently attributed the warming to the greenhouse effect [e.g., Wallace and Hobbs, 2006; Le Treut et al., 2007; American Meteorological Society, 2000].

  15. Spectral Characteristic of Tholin Produced from Possible Early Earth Atmospheres and its Role in Antigreenhouse Effect on Early Earth

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Imanaka, H.; Wilhite, P.; McKay, C.; Bakes, E.; Cruikshank, D. P.; Arakawa, E. T.

    2003-01-01

    We have produced organic material simulating a methane photochemical haze in a CO2- rich atmosphere of the early Earth by irradiating gas mixtures in an inductively coupled cold plasma chamber with pressure approx. 0.25 mbar at 100 W total power. The flow rate was 24 cm3 min. We added progressively higher levels of CH, by combining gas mixtures of N2/CH4 (9/1) and N2/CO2 (9/1) to change the ratio of CH4/CO2. Tholin was accumulated for 5 hours in each experiment; the onset of tholin formation is in the range CH4/CO2 = 0.5 to 1. As the mixing ratio of CH, is increased, the production rate of the brownish tholin film increases. IR spectra showed the C-H and N-H bands similar to that of Titan tholin and closely resemble Titan tholin made at 0.13 mbar pressure. A decrease in the CH bonds on decreasing CH4/CO2 is noted. Ether bands (-(2-O-C) were tentatively detected, but no detectable carbonyl (C=O) band was found. The absorption in the UV region for the early Earth tholin is found to be substantially greater than the Titan tholin. Quantitative values of the optical constants of early Earth tholin are currently being measured.

  16. Spectral Characteristic of Tholin Produced from Possible Early Earth Atmospheres and its Role in Antigreenhouse Effect on Early Earth

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Imanaka, H.; Wilhite, P.; McKay, C.; Bakes, E.; Cruikshank, D. P.; Arakawa, E. T.

    2003-01-01

    We have produced organic material simulating a methane photochemical haze in a CO2- rich atmosphere of the early Earth by irradiating gas mixtures in an inductively coupled cold plasma chamber with pressure approx. 0.25 mbar at 100 W total power. The flow rate was 24 cm3 min. We added progressively higher levels of CH, by combining gas mixtures of N2/CH4 (9/1) and N2/CO2 (9/1) to change the ratio of CH4/CO2. Tholin was accumulated for 5 hours in each experiment; the onset of tholin formation is in the range CH4/CO2 = 0.5 to 1. As the mixing ratio of CH, is increased, the production rate of the brownish tholin film increases. IR spectra showed the C-H and N-H bands similar to that of Titan tholin and closely resemble Titan tholin made at 0.13 mbar pressure. A decrease in the CH bonds on decreasing CH4/CO2 is noted. Ether bands (-(2-O-C) were tentatively detected, but no detectable carbonyl (C=O) band was found. The absorption in the UV region for the early Earth tholin is found to be substantially greater than the Titan tholin. Quantitative values of the optical constants of early Earth tholin are currently being measured.

  17. Co-Seismic Mass Dislocation and Its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.

    1999-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the "shaking" that is the earthquake, leaves behind permanent (step-function-like) dislocations in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field (in terms of spherical harmonic Stokes coefficients). The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results. The calculation uses the normal mode summation scheme, applied to 15,814 major earthquakes that occurred during 1976-1998, according to source mechanism solutions given by the Harvard Central Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies. For example, earthquakes conspire to decrease J(sub 2) and J(sub 22) while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to "nudge" the Earth rotation pole towards about 140 degree E, roughly opposite to the observed polar drift direction. The geophysical significance and implications will be further studied.

  18. The effects of refraction on transit transmission spectroscopy: application to Earth-like exoplanets

    SciTech Connect

    Misra, Amit; Meadows, Victoria; Crisp, Dave

    2014-09-01

    We quantify the effects of refraction in transit transmission spectroscopy on spectral absorption features and on temporal variations that could be used to obtain altitude-dependent spectra for planets orbiting stars of different stellar types. We validate our model against altitude-dependent transmission spectra of the Earth from ATMOS and against lunar eclipse spectra from Pallé et al. We perform detectability studies to show the potential effects of refraction on hypothetical observations of Earth analogs with the James Webb Space Telescope NIRSPEC. Due to refraction, there will be a maximum tangent pressure level that can be probed during transit for each given planet-star system. We show that because of refraction, for an Earth-analog planet orbiting in the habitable zone of a Sun-like star only the top 0.3 bars of the atmosphere can be probed, leading to a decrease in the signal-to-noise ratio (S/N) of absorption features by 60%, while for an Earth-analog planet orbiting in the habitable zone of an M5V star it is possible to probe almost the entire atmosphere with minimal decreases in S/N. We also show that refraction can result in temporal variations in the transit transmission spectrum which may provide a way to obtain altitude-dependent spectra of exoplanet atmospheres. Additionally, the variations prior to ingress and subsequent to egress provide a way to probe pressures greater than the maximum tangent pressure that can be probed during transit. Therefore, probing the maximum range of atmospheric altitudes, and in particular the near-surface environment of an Earth-analog exoplanet, will require looking at out-of-transit refracted light in addition to the in-transit spectrum.

  19. Co-Seismic Mass Dislocation and Its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.

    1999-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the "shaking" that is the earthquake, leaves behind permanent (step-function-like) dislocations in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field (in terms of spherical harmonic Stokes coefficients). The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results. The calculation uses the normal mode summation scheme, applied to 15,814 major earthquakes that occurred during 1976-1998, according to source mechanism solutions given by the Harvard Central Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies. For example, earthquakes conspire to decrease J(sub 2) and J(sub 22) while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to "nudge" the Earth rotation pole towards about 140 degree E, roughly opposite to the observed polar drift direction. The geophysical significance and implications will be further studied.

  20. Co-Seismic Mass Displacement and its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Gross, R. S.

    2004-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the "shaking" that is the earthquake, leaves behind permanent (step-function-like) displacements in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field. The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results based on Chao & Gross. The calculation uses the normal mode summation scheme, applied to over twenty thousand major earthquakes that occurred during 1976-2002, according to source mechanism solutions given by the Harvard Centroid Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies, conspiring to decrease J2 and J22 while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to "nudge" the Earth rotation pole towards approx. 140 deg.E, roughly opposite to the observed polar drift direction. Currently, the Gravity Recovery And Climate Experiment (GRACE) is measuring the time-variable gravity to high degree and order with unprecedented accuracy. Our results show that great earthquakes such as the 1960 Chilean or 1964 Alaskan events cause gravitational field changes that are large enough to be detected by GRACE.

  1. Co-Seismic Mass Dislocation and its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Gross, R. S.

    2002-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the shaking that is the earthquake, leaves behind permanent (step-function-like) dislocations in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field (in terms of spherical harmonic Stokes coefficients). The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results based on Chao & Gross (1987). The calculation uses the normal mode summation scheme, applied to nearly twenty thousand major earthquakes that occurred during 1976-2002, according to source mechanism solutions given by the Harvard Central Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies. For example, earthquakes conspire to decrease J2 and J22 while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to nudge the Earth rotation pole towards approximately 140 degrees E, roughly opposite to the observed polar drift direction. The geophysical significance and implications will be further studied.

  2. Effect of Earth and Mars departure delays on human missions to Mars

    NASA Technical Reports Server (NTRS)

    Desai, Prasun N.; Tartabini, Paul V.

    1993-01-01

    This study determines the impact on the initial mass in low-Earth orbit (IMLEO) for delaying departure from Mars and Earth by 5, 15, and 30 days, once a nominal mission to Mars has been selected. Additionally, the use of a deep space maneuver (DSM) is attempted to alleviate the IMLEO penalties. Three different classes of missions are analyzed using chemical and nuclear thermal propulsion systems in the 2000-2025 time-frame: opposition, conjunction, and fast-transfer conjunction. The results indicate that Mars and Earth delays can lead to large IMLEO penalties. Opposition and fast-transfer conjunction class missions have the highest IMLEO penalties, upwards of 432.4 mt and 1977.3 mt, respectively. Conjunction class missions, on the other hand, tend to be insensitive to Mars and Earth delays having IMLEO penalties under 103.5 mt. As expected, nuclear thermal propulsion had significantly lower IMLEO penalties as compared to chemical propulsion. The use of a DSM is found not to have a significant impact on reducing the IMLEO penalties. Through this investigation, the effect of off-nominal departure conditions on the overall mission (i.e., IMLEO) can be gained, enabling mission designers to incorporate the influence of off-nominal departure conditions of the interplanetary trajectory in the overall conceptual design process of a Mars transfer vehicle.

  3. Effects of the same CIR on the plasma environment of Venus, Earth and Mars

    NASA Astrophysics Data System (ADS)

    Opitz, A.; Witasse, O.; Svedhem, H.; Sauvaud, J.-A.; Fedorov, A.

    2013-09-01

    During the recent solar activity minimum the solar wind streams were very persistent, even after a few solar rotations the global solar wind properties were unchanged. The compression regions due to the fast stream - slow stream interaction were sweeping through the ecliptic plane without large longitudinal alterations, these are named corotating interaction regions (CIR). Their persistence allows the comparison of the effects of the same CIR on the different terrestrial planets. We investigated the time period in January and February 2007, when the twin solar spacecraft STEREO were still nearby Earth observing simultaneously the solar wind and the terrestrial magnetotail. When considering the solar rotation and the corotating solar wind structures, Venus was ~10 days ahead Earth, while Mars ~10 days behind. For this reason, the Venus Express in-situ plasma and magnetic field measurements were shifted by such a timelag to Earth orbit, and respectively the Mars Express observations in order to find the corresponding CIRs. Since the investigated three planets have different magnetic characteristics, their response to the CIR passage is expected to be different. We find energetic particle bursts escaping from the magnetized Earth and the unmagnetized planets Venus and Mars have increased ion escape rates.

  4. Effect of Earth and Mars departure delays on human missions to Mars

    NASA Astrophysics Data System (ADS)

    Desai, Prasun N.; Tartabini, Paul V.

    1993-08-01

    This study determines the impact on the initial mass in low-Earth orbit (IMLEO) for delaying departure from Mars and Earth by 5, 15, and 30 days, once a nominal mission to Mars has been selected. Additionally, the use of a deep space maneuver (DSM) is attempted to alleviate the IMLEO penalties. Three different classes of missions are analyzed using chemical and nuclear thermal propulsion systems in the 2000-2025 time-frame: opposition, conjunction, and fast-transfer conjunction. The results indicate that Mars and Earth delays can lead to large IMLEO penalties. Opposition and fast-transfer conjunction class missions have the highest IMLEO penalties, upwards of 432.4 mt and 1977.3 mt, respectively. Conjunction class missions, on the other hand, tend to be insensitive to Mars and Earth delays having IMLEO penalties under 103.5 mt. As expected, nuclear thermal propulsion had significantly lower IMLEO penalties as compared to chemical propulsion. The use of a DSM is found not to have a significant impact on reducing the IMLEO penalties. Through this investigation, the effect of off-nominal departure conditions on the overall mission (i.e., IMLEO) can be gained, enabling mission designers to incorporate the influence of off-nominal departure conditions of the interplanetary trajectory in the overall conceptual design process of a Mars transfer vehicle.

  5. Effect of Earth and Mars departure delays on human missions to Mars

    NASA Technical Reports Server (NTRS)

    Desai, Prasun N.; Tartabini, Paul V.

    1993-01-01

    This study determines the impact on the initial mass in low-Earth orbit (IMLEO) for delaying departure from Mars and Earth by 5, 15, and 30 days, once a nominal mission to Mars has been selected. Additionally, the use of a deep space maneuver (DSM) is attempted to alleviate the IMLEO penalties. Three different classes of missions are analyzed using chemical and nuclear thermal propulsion systems in the 2000-2025 time-frame: opposition, conjunction, and fast-transfer conjunction. The results indicate that Mars and Earth delays can lead to large IMLEO penalties. Opposition and fast-transfer conjunction class missions have the highest IMLEO penalties, upwards of 432.4 mt and 1977.3 mt, respectively. Conjunction class missions, on the other hand, tend to be insensitive to Mars and Earth delays having IMLEO penalties under 103.5 mt. As expected, nuclear thermal propulsion had significantly lower IMLEO penalties as compared to chemical propulsion. The use of a DSM is found not to have a significant impact on reducing the IMLEO penalties. Through this investigation, the effect of off-nominal departure conditions on the overall mission (i.e., IMLEO) can be gained, enabling mission designers to incorporate the influence of off-nominal departure conditions of the interplanetary trajectory in the overall conceptual design process of a Mars transfer vehicle.

  6. Earth remote sensing as an effective tool for the development of advanced innovative educational technologies

    NASA Astrophysics Data System (ADS)

    Mayorova, Vera; Mayorov, Kirill

    2009-11-01

    Current educational system is facing a contradiction between the fundamentality of engineering education and the necessity of applied learning extension, which requires new methods of training to combine both academic and practical knowledge in balance. As a result there are a number of innovations being developed and implemented into the process of education aimed at optimizing the quality of the entire educational system. Among a wide range of innovative educational technologies there is an especially important subset of educational technologies which involve learning through hands-on scientific and technical projects. The purpose of this paper is to describe the implementation of educational technologies based on small satellites development as well as the usage of Earth remote sensing data acquired from these satellites. The increase in public attention to the education through Earth remote sensing is based on the concern that although there is a great progress in the development of new methods of Earth imagery and remote sensing data acquisition there is still a big question remaining open on practical applications of this kind of data. It is important to develop the new way of thinking for the new generation of people so they understand that they are the masters of their own planet and they are responsible for its state. They should desire and should be able to use a powerful set of tools based on modern and perspective Earth remote sensing. For example NASA sponsors "Classroom of the Future" project. The Universities Space Research Association in United States provides a mechanism through which US universities can cooperate effectively with one another, with the government, and with other organizations to further space science and technology, and to promote education in these areas. It also aims at understanding the Earth as a system and promoting the role of humankind in the destiny of their own planet. The Association has founded a Journal of Earth System

  7. Possible Effect of the Earth's Inertial Induction on the Orbital Decay of LAGEOS

    NASA Astrophysics Data System (ADS)

    Dey, Ujjal; Kar, Samanwita; Ghosh, Amitabha

    2016-09-01

    The theory of velocity dependent inertial induction, based upon extended Mach's principle, has been able to generate many interesting results related to celestial mechanics and cosmological problems. Because of the extremely minute magnitude of the effect its presence can be detected through the motion of accurately observed bodies like Earth satellites. LAGEOS I and II are medium altitude satellites with nearly circular orbits. The motions of these satellites are accurately recorded and the past data of a few decades help to test many theories including the general theory of relativity. Therefore, it is hoped that the effect of the Earth's inertial induction can have any detectable effect on the motion of these satellites. It is established that the semi-major axis of LAGEOS I is decreasing at the rate of 1.3 mm/d. As the atmospheric drag is negligible at that altitude, a proper explanation of the secular change has been wanting, and, therefore, this paper examines the effect of the Earth's inertial induction effect on LAGEOS I. Past researches have established that Yarkovsky thermal drag, charged and neutral particle drag might be the possible mechanisms for this orbital decay. Inertial induction is found to generate a perturbing force that results in 0.33 mm/d decay of the semi major axis. Some other changes are also predicted and the phenomenon also helps to explain the observed changes in the orbits of a few other satellites. The results indicate the feasibility of the theory of inertial induction i.e. the dynamic gravitation phenomenon of the Earth on its satellites as a possible partial cause for orbital decay.

  8. Thermal evolution of the earth - Effects of volatile exchange between atmosphere and interior

    NASA Technical Reports Server (NTRS)

    Mcgovern, Patrick J.; Schubert, Gerald

    1989-01-01

    The thermal history of the earth is investigated using a parameterized model of mantle convection, that includes the effects of volatile exchange between the mantle and the surface reservoir and the softening of the mantle by the dissolved volatiles. The mantle degassing rate is taken to be directly proportional to the rate of seafloor spreading which depends on the mantle heat flow. It is shown that the dependence of the mantle viscosity on the volatile content has important effects on the thermal evolution of planetary interiors and the evolution of planetary atmospheres. Degassing is compensated by an increase in temperature, while regassing is compensated by a decrease in temperature. Reasonable degassing scenarios can account for an early rapid formation of the earth's atmosphere inferred from noble gas abundances.

  9. Dynamic effect of metro-induced vibration on the rammed earth base of the Bell Tower.

    PubMed

    Lai, Jinxing; Niu, Fangyuan; Wang, Ke; Chen, Jianxun; Qiu, Junling; Fan, Haobo; Hu, Zhinan

    2016-01-01

    Xi'an Bell Tower (the Bell Tower) is a state-level ancient relic in China. The vibration caused by metro will exert adverse effect on the Bell Tower. This paper aims at presenting 3D-FEM models to predict the peak period velocity (PPV) of rammed earth base when the metro passing through the Bell Tower. The calculation results are compared with those of field test. Both results were found to be in good agreement. Furthermore, the results indicated that the effect of shock absorption measures is significant. The shock absorption tracks can obviously decrease the vibration of the Bell Tower, and the maximum decrease of PPV of the rammed earth base is 78.91 %. The proposed prediction has the potential to be developed as a decision and management tool for the evaluation of the risk associated with the influence of vibration caused by metro on buildings in urban areas.

  10. Effects of inherent alkali and alkaline earth metallic species on biomass pyrolysis at different temperatures.

    PubMed

    Hu, Song; Jiang, Long; Wang, Yi; Su, Sheng; Sun, Lushi; Xu, Boyang; He, Limo; Xiang, Jun

    2015-09-01

    This work aimed to investigate effects of inherent alkali and alkaline earth metallic species (AAEMs) on biomass pyrolysis at different temperatures. The yield of CO, H2 and C2H4 was increased and that of CO2 was suppressed with increasing temperature. Increasing temperature could also promote depolymerization and aromatization reactions of active tars, forming heavier polycyclic aromatic hydrocarbons, leading to decrease of tar yields and species diversity. Diverse performance of inherent AAEMs at different temperatures significantly affected the distribution of pyrolysis products. The presence of inherent AAEMs promoted water-gas shift reaction, and enhanced the yield of H2 and CO2. Additionally, inherent AAEMs not only promoted breakage and decarboxylation/decarbonylation reaction of thermally labile hetero atoms of the tar but also enhanced thermal decomposing of heavier aromatics. Inherent AAEMs could also significantly enhance the decomposition of levoglucosan, and alkaline earth metals showed greater effect than alkali metals. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Effect of Rheology on Mantle Dynamics and Plate Tectonics in Super-Earths

    NASA Astrophysics Data System (ADS)

    Tackley, P. J.; Ammann, M. W.; Brodholt, J. P.; Dobson, D. P.; Valencia, D. C.

    2011-12-01

    The discovery of extra-solar "super-Earth" planets with sizes up to twice that of Earth has prompted interest in their possible lithosphere and mantle dynamics and evolution. Simple scalings [1,2] suggest that super-Earths are more likely than an equivalent Earth-sized planet to be undergoing plate tectonics. Generally, viscosity and thermal conductivity increase with pressure while thermal expansivity decreases, resulting in lower convective vigor in the deep mantle, which, if extralopated to the largest super-Earths might, according to conventional thinking, result a very low effective Rayleigh number in their deep mantles and possibly no convection there. Here we evaluate this. (i) As the mantle of a super-Earth is made mostly of post-perovskite we here extend the density functional theory (DFT) calculations of post-perovskite activation enthalpy of [3] to a pressure of 1 TPa. The activation volume for diffusion creep becomes very low at very high pressure, but nevertheless for the largest super-Earths the viscosity along an adiabat may approach 10^30 Pa s in the deep mantle, which would be too high for convection. (ii) We use these DFT-calculated values in numerical simulations of mantle convection and lithosphere dynamics of planets with up to ten Earth masses. The models assume a compressible mantle including depth-dependence of material properties and plastic yielding induced plate-like lithospheric behavior, solved using StagYY [4]. Results confirm the likelihood of plate tectonics and show a novel self-regulation of deep mantle temperature. The deep mantle is not adiabatic; instead internal heating raises the temperature until the viscosity is low enough to facilitate convective loss of the radiogenic heat, which results in a super-adiabatic temperature profile and a viscosity increase with depth of no more than ~3 orders of magnitude, regardless of what is calculated for an adiabat. It has recently been argued [5] that at very high pressures, deformation

  12. The effects from high-altitude storm discharges in Earth atmosphere

    NASA Astrophysics Data System (ADS)

    Kozak, L.; Odzimek, A.; Ivchenko, V.; Kozak, P.; Gala, I.; Lapchuk, V.

    2016-06-01

    The regularities of appearance of transient luminous effects in Earth atmosphere and features of their ground-based observations are considered. Using video-observations obtained in the Institution of Geophysics of Poland Academy of Sciences the energy of atmospheric afterglow from these processes in visual wavelength range has been determined. Calibrating curve was plotted using unfocal images of Vega. The star spectrum,atmosphere absorption coefficient and characteristics of the observational camera were used.

  13. Preliminary Results on the Gravitational Slingshot Effect and the Population of Hyperbolic Meteoroids at Earth

    NASA Technical Reports Server (NTRS)

    Wiegert, P. A.

    2011-01-01

    Interstellar meteoroids, solid particles arriving from outside our Solar System, are not easily distinguished from local meteoroids. A velocity above the escape velocity of the Sun is often used as an indicator of a possible interstellar origin. We demonstrate that the gravitational slingshot effect, resulting from the passage of local meteoroid near a planet, can produce hyperbolic meteoroids at the Earth s orbit with excess velocities comparable to those expected of interstellar meteoroids.

  14. Effects of Variable Eccentricity on the Climate of an Earth-Like World

    NASA Technical Reports Server (NTRS)

    Way, M. J.; Georgakarakos, Nikolaos

    2017-01-01

    The Kepler era of exoplanetary discovery has presented the Astronomical community with a cornucopia of planetary systems very different from the one which we inhabit. It has long been known that Jupiter plays a major role in the orbital parameters of Mars and its climate, but there is also a long-standing belief that Jupiter would play a similar role for Earth if not for its large moon. Using a three dimensional general circulation model (3-D GCM) with a fully-coupled ocean we simulate what would happen to the climate of an Earth-like world if Mars did not exist, but a Jupiter-like planet was much closer to Earths orbit. We investigate two scenarios that involve evolution of the Earth-like planets orbital eccentricity from 0 to 0.066 on a time scale of 4500 years, and from 0 to 0.283 over 6500 years. We discover that during most of the 6500 year scenario the planet would experience a moist greenhouse effect when near periastron. This could have implications for the ability of such a world to retain an ocean on time scales of 109 years. More Earth-like planets in multi-planet systems will be discovered as we continue to survey the skies and the results herein show that the proximity of large gas giant planets may play an important role in the habitabilty of these worlds. These are the first such 3-D GCM simulations using a fully-coupled ocean with a planetary orbit that evolves over time due to the presence of a giant planet.

  15. EFFECT OF UV RADIATION ON THE SPECTRAL FINGERPRINTS OF EARTH-LIKE PLANETS ORBITING M STARS

    SciTech Connect

    Rugheimer, S.; Kaltenegger, L.; Segura, A.; Linsky, J.; Mohanty, S.

    2015-08-10

    We model the atmospheres and spectra of Earth-like planets orbiting the entire grid of M dwarfs for active and inactive stellar models with T{sub eff} = 2300 K to T{sub eff} = 3800 K and for six observed MUSCLES M dwarfs with UV radiation data. We set the Earth-like planets at the 1 AU equivalent distance and show spectra from the visible to IR (0.4–20 μm) to compare detectability of features in different wavelength ranges with the James Webb Space Telescope and other future ground- and spaced-based missions to characterize exo-Earths. We focus on the effect of UV activity levels on detectable atmospheric features that indicate habitability on Earth, namely, H{sub 2}O, O{sub 3}, CH{sub 4}, N{sub 2}O, and CH{sub 3}Cl. To observe signatures of life—O{sub 2}/O{sub 3} in combination with reducing species like CH{sub 4}—we find that early and active M dwarfs are the best targets of the M star grid for future telescopes. The O{sub 2} spectral feature at 0.76 μm is increasingly difficult to detect in reflected light of later M dwarfs owing to low stellar flux in that wavelength region. N{sub 2}O, another biosignature detectable in the IR, builds up to observable concentrations in our planetary models around M dwarfs with low UV flux. CH{sub 3}Cl could become detectable, depending on the depth of the overlapping N{sub 2}O feature. We present a spectral database of Earth-like planets around cool stars for directly imaged planets as a framework for interpreting future light curves, direct imaging, and secondary eclipse measurements of the atmospheres of terrestrial planets in the habitable zone to design and assess future telescope capabilities.

  16. The Role of Stereo Projection in Developing an Effective Concluding Earth Science Course

    NASA Astrophysics Data System (ADS)

    Kirkby, K. C.; Morin, P. J.; Finley, F.

    2003-12-01

    Remarkably few students enrolled in introductory earth science courses have any intention of continuing in earth science, and for most students, these classes are often the last science course they will take in their academic careers. These students would be better served, if the course was instead designed to be a 'concluding' science course. One that explicitly provided students with the knowledge they need to become more informed citizens in the global community. The University of Minnesota is attempting to develop a national model of an effective 'concluding' earth science course by integrating three essential approaches: use of regional case studies to increase student comprehension; a comprehensive evaluation of students' prior knowledge, misconceptions and post-instructional knowledge that is woven throughout the project; and, an ambitious use of 'GeoWall' stereo projection systems to facilitate the students' use of maps and data sets and level the classroom playing field with regard to spatial conceptualization. In every discipline there are some critical skills or assessments that serve as conscious or unconscious 'gate-keepers' for progress in that field. In earth science, map interpretation is probably the critical restriction curtailing students' ability to access and explore course concepts. So much of our discipline's information is encoded in maps, that students who are not innately predisposed to understanding maps find it difficult to understand much of the course content and methodology. GeoWall stereo projection systems can reduce the efficiency of this 'gate-keeping' process, allowing students of diverse backgrounds and abilities to understand map data and succeed in the course. In doing so, these systems will not only help increase students' scientific literacy, but may also greatly increase the diversity of students who do go on to consider earth science as a potential career.

  17. Effect of UV Radiation on the Spectral Fingerprints of Earth-like Planets Orbiting M Stars

    NASA Astrophysics Data System (ADS)

    Rugheimer, S.; Kaltenegger, L.; Segura, A.; Linsky, J.; Mohanty, S.

    2015-08-01

    We model the atmospheres and spectra of Earth-like planets orbiting the entire grid of M dwarfs for active and inactive stellar models with Teff = 2300 K to Teff = 3800 K and for six observed MUSCLES M dwarfs with UV radiation data. We set the Earth-like planets at the 1 AU equivalent distance and show spectra from the visible to IR (0.4-20 μm) to compare detectability of features in different wavelength ranges with the James Webb Space Telescope and other future ground- and spaced-based missions to characterize exo-Earths. We focus on the effect of UV activity levels on detectable atmospheric features that indicate habitability on Earth, namely, H2O, O3, CH4, N2O, and CH3Cl. To observe signatures of life—O2/O3 in combination with reducing species like CH4—we find that early and active M dwarfs are the best targets of the M star grid for future telescopes. The O2 spectral feature at 0.76 μm is increasingly difficult to detect in reflected light of later M dwarfs owing to low stellar flux in that wavelength region. N2O, another biosignature detectable in the IR, builds up to observable concentrations in our planetary models around M dwarfs with low UV flux. CH3Cl could become detectable, depending on the depth of the overlapping N2O feature. We present a spectral database of Earth-like planets around cool stars for directly imaged planets as a framework for interpreting future light curves, direct imaging, and secondary eclipse measurements of the atmospheres of terrestrial planets in the habitable zone to design and assess future telescope capabilities.

  18. The effect of cloud type on Earth's energy balance - Global analysis

    NASA Technical Reports Server (NTRS)

    Hartmann, Dennis L.; Ockert-Bell, Maureen E.; Michelsen, Marc L.

    1992-01-01

    The role of fractional area coverage by cloud types in the energy balance of the earth is investigated through joint use of International Satellite Cloud Climatology Project (ISCCP) C1 cloud data and Earth Radiation Budget Experiment (ERBE) broadband energy flux data for the one-year period March 1985 through February 1986. Multiple linear regression is used to relate the radiation budget data to the cloud data. Comparing cloud forcing estimates obtained from the ISCCP-ERBE regression with those derived from the ERBE scene identification shows generally good agreement except over snow, in tropical convective regions, and in regions that are either nearly cloudless or always overcast. It is suggested that a substantial fraction of the disagreement in longwave cloud forcing in tropical convective regions is associated with the fact that the ERBE scene identification does not take into account variations in upper-tropospheric water vapor. On a global average basis, low clouds make the largest contribution to the net energy balance of the Earth, because they cover such a large area and because their albedo effect dominates their effect on emitted thermal radiation. High, optically thick clouds can also very effectively reduce the energy balance, however, because their very high albedos overcome their low emission temperatures.

  19. The effect of cloud type on Earth's energy balance - Global analysis

    NASA Technical Reports Server (NTRS)

    Hartmann, Dennis L.; Ockert-Bell, Maureen E.; Michelsen, Marc L.

    1992-01-01

    The role of fractional area coverage by cloud types in the energy balance of the earth is investigated through joint use of International Satellite Cloud Climatology Project (ISCCP) C1 cloud data and Earth Radiation Budget Experiment (ERBE) broadband energy flux data for the one-year period March 1985 through February 1986. Multiple linear regression is used to relate the radiation budget data to the cloud data. Comparing cloud forcing estimates obtained from the ISCCP-ERBE regression with those derived from the ERBE scene identification shows generally good agreement except over snow, in tropical convective regions, and in regions that are either nearly cloudless or always overcast. It is suggested that a substantial fraction of the disagreement in longwave cloud forcing in tropical convective regions is associated with the fact that the ERBE scene identification does not take into account variations in upper-tropospheric water vapor. On a global average basis, low clouds make the largest contribution to the net energy balance of the Earth, because they cover such a large area and because their albedo effect dominates their effect on emitted thermal radiation. High, optically thick clouds can also very effectively reduce the energy balance, however, because their very high albedos overcome their low emission temperatures.

  20. The Earth Exploration Toolbook: Scaffolding Access and Use of Earth Science Data to Promote Effective Inquiry Investigations by Students

    NASA Astrophysics Data System (ADS)

    Ledley, T. S.; Dahlman, L.; McAuliffe, C.; Haddad, N.

    2007-12-01

    The Earth Exploration Toolbook (EET, http://serc.carleton.edu/eet) is an online collection of computer-based Earth science activities. Each activity, or chapter, introduces one or more data sets and an analysis tool that enables users to explore some aspect of the Earth system. Series of step-by-step instructions show users how to 1) access the data and analysis tool and install it if necessary, 2) examine, visualize, and interpret the data, and 3) conduct a data-based investigation using the data and analysis tool. Step-by-step instructions walk users through valid scientific inquiries of the data to produce a map, graph, or other data product. The implicit goal of each chapter though, is to build the skills and confidence of teachers and students to enable them to learn and teach with data. When educators become familiar enough with data and analysis tools, they can adapt the use of data to match their curriculum and their students" abilities. This enables educators to promote a greater use of inquiry into students learning of scientific concepts. EET chapters are rich launching points for inquiry. Embedded open-ended questions ask users to consider various aspects of the data. These questions can begin the process of guided inquiry. The "Going Further" section of each EET chapter provides ideas for independent investigations, using another dataset or employing the same analysis strategy with a different analysis tool. At least one chapter inspired an award-winning high school science fair project. In this session we will examine the components of EET chapters that promote inquiry, describe the use of EET chapters in our teacher professional development programs, and give examples of how these programs have impacted participating teachers" use of data, analysis tools, and inquiry in their teaching.

  1. Spin-orbit coupling in octamers in the spinel sulfide CuIr2S4: Competition between spin-singlet and quadrupolar states and its relevance to remnant paramagnetism

    NASA Astrophysics Data System (ADS)

    Nasu, Joji; Motome, Yukitoshi

    2014-07-01

    We theoretically investigate magnetic properties in the low-temperature phase with the formation of eight-site clusters, octamers, in the spinel compound CuIr2S4. The octamer state was considered to be a spin-singlet state induced by a Peierls instability through the strong anisotropy of d orbitals, the so-called orbital Peierls state. We reexamine this picture by taking into account the spin-orbit coupling, which was ignored in the previous study. We derive a low-energy effective model between jeff=1/2 quasispins on Ir4+ cations in an octamer from the multiorbital Hubbard model with the strong spin-orbit coupling by performing the perturbation expansion from the strong correlation limit. The effective Hamiltonian is in the form of the Kitaev-Heisenberg model but with an additional interaction, a symmetric off-diagonal exchange interaction originating from the perturbation process including both d-d and d-p-d hoppings. Analyzing the effective Hamiltonian on two sites and the octamer by the exact diagonalization, we find that there is competition between a spin-singlet state and a quadrupolar state. The former singlet state is a conventional one, adiabatically connected to the orbital Peierls state. On the other hand, the latter quadrupolar state is stabilized by the additional interaction, which consists of a linear combination of different total spin momenta along the spin quantization axis. In the competing region, the model exhibits paramagnetic behavior with a renormalized small effective moment at low temperature. This peculiar remnant paramagnetism is not obtained in the Kitaev-Heisenberg model without the additional interaction. Our results renew the picture of the octamer state and provide a scenario for the intrinsic paramagnetic behavior recently observed in a muon spin rotation experiment [K. M. Kojima et al., Phys. Rev. Lett. 112, 087203 (2014)]., 10.1103/PhysRevLett.112.087203

  2. On the average temperature of airless spherical bodies and the magnitude of Earth's atmospheric thermal effect.

    PubMed

    Volokin, Den; ReLlez, Lark

    2014-01-01

    The presence of atmosphere can appreciably warm a planet's surface above the temperature of an airless environment. Known as a natural Greenhouse Effect (GE), this near-surface Atmospheric Thermal Enhancement (ATE) as named herein is presently entirely attributed to the absorption of up-welling long-wave radiation by greenhouse gases. Often quoted as 33 K for Earth, GE is estimated as a difference between planet's observed mean surface temperature and an effective radiating temperature calculated from the globally averaged absorbed solar flux using the Stefan-Boltzmann (SB) radiation law. This approach equates a planet's average temperature in the absence of greenhouse gases or atmosphere to an effective emission temperature assuming ATE ≡ GE. The SB law is also routinely employed to estimating the mean temperatures of airless bodies. We demonstrate that this formula as applied to spherical objects is mathematically incorrect owing to Hölder's inequality between integrals and leads to biased results such as a significant underestimation of Earth's ATE. We derive a new expression for the mean physical temperature of airless bodies based on an analytic integration of the SB law over a sphere that accounts for effects of regolith heat storage and cosmic background radiation on nighttime temperatures. Upon verifying our model against Moon surface temperature data provided by the NASA Diviner Lunar Radiometer Experiment, we propose it as a new analytic standard for evaluating the thermal environment of airless bodies. Physical evidence is presented that Earth's ATE should be assessed against the temperature of an equivalent airless body such as the Moon rather than a hypothetical atmosphere devoid of greenhouse gases. Employing the new temperature formula we show that Earth's total ATE is ~90 K, not 33 K, and that ATE = GE + TE, where GE is the thermal effect of greenhouse gases, while TE > 15 K is a thermodynamic enhancement independent of the

  3. Effects of Earth's rotation on the early differentiation of a terrestrial magma ocean

    NASA Astrophysics Data System (ADS)

    Maas, Christian; Hansen, Ulrich

    2015-11-01

    Similar to other terrestrial planets like Moon and Mars, Earth experienced a magma ocean period about 4.5 billion years ago. On Earth differentiation processes in the magma ocean set the initial conditions for core formation and mantle evolution. During the magma ocean period Earth was rotating significantly faster than today. Further, the viscosity of the magma was low, thus that planetary rotation potentially played an important role for differentiation. However, nearly all previous studies neglect rotational effects. All in all, our results suggest that planetary rotation plays an important role for magma ocean crystallization. We employ a 3-D numerical model to study crystal settling in a rotating and vigorously convecting early magma ocean. We show that crystal settling in a terrestrial magma ocean is crucially affected by latitude as well as by rotational strength and crystal density. Due to rotation an inhomogeneous accumulation of crystals during magma ocean solidification with a distinct crystal settling between pole and equator could occur. One could speculate that this may have potentially strong effects on the magma ocean solidification time and the early mantle composition. It could support the development of a basal magma ocean and the formation of anomalies at the core-mantle boundary in the equatorial region, reaching back to the time of magma ocean solidification.

  4. Theory connecting nonlocal sediment transport, earth surface roughness, and the Sadler effect

    NASA Astrophysics Data System (ADS)

    Schumer, Rina; Taloni, Alessandro; Furbish, David Jon

    2017-03-01

    Earth surface evolution, like many natural phenomena typified by fluctuations on a wide range of scales and deterministic smoothing, results in a statistically rough surface. We present theory demonstrating that scaling exponents of topographic and stratigraphic statistics arise from long-time averaging of noisy surface evolution rather than specific landscape evolution processes. This is demonstrated through use of "elastic" Langevin equations that generically describe disturbance from a flat earth surface using a noise term that is smoothed deterministically via sediment transport. When smoothing due to transport is a local process, the geologic record self organizes such that a specific Sadler effect and topographic power spectral density (PSD) emerge. Variations in PSD slope reflect the presence or absence and character of nonlocality of sediment transport. The range of observed stratigraphic Sadler slopes captures the same smoothing feature combined with the presence of long-range spatial correlation in topographic disturbance.

  5. Compact High Current Rare-Earth Emitter Hollow Cathode for Hall Effect Thrusters

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R. (Inventor); Goebel, Dan M. (Inventor); Watkins, Ronnie M. (Inventor)

    2012-01-01

    An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

  6. Seismic effects on the rotational dynamics of the earth and its gravitational field

    NASA Technical Reports Server (NTRS)

    Sanchez, B. V.

    1976-01-01

    The effects of earthquakes on the rotational motion of the earth were studied. The connection between the fault parameters and the corresponding changes in the moments and products of inertia were analytically developed. The reciprocal theorem of elasticity and Volterra's formula were applied as well as the displacement and stress fields for the second degree static response of the earth model being used. The numerical results of the investigation yield the magnitude and direction of the pole shift as well as the change in the length of the day. The changes in the second degree coefficients of the geopotential were computed. Source parameters corresponding to the Alaskan earthquake on March 28, 1964 were used to generate numerical results.

  7. The Pale Orange Dot: Spectral Effects of a Hazy Early Earth

    NASA Astrophysics Data System (ADS)

    Arney, G. N.; Meadows, V. S.; Domagal-Goldman, S. D.; Claire, M.; Schwieterman, E.

    2014-12-01

    Increasing evidence suggests Archean Earth had a photochemical hydrocarbon haze similar to Titan's (Zerkle et al. 2012), with important climate implications (Pavlov et al. 2001, Trainer et al. 2006, Haqq-Misra et al. 2008, Domagal-Goldman et al. 2008, Wolf and Toon 2012). Observations also suggest hazy exoplanets are common (Sing et al. 2011, Kreidberg et al 2014), so hazy planet spectra will be relevant to future exoplanet spectral characterization missions. Here, we consider the implications of hydrocarbon aerosols on the spectrum of Archean Earth, examining the effect of a haze layer on the detectability of spectral features from putative biosignatures and the Rayleigh scattering slope. We also examine haze's impact on the spectral energy distribution at the planetary surface, which may be important to the co-evolution of life with its environment. Because the atmospheric pressure and haze particle composition of the Archean Earth are poorly constrained, we test the impact of atmospheric pressure and particle density on haze formation. Our study uses a modified version of the 1-D photochemical code developed originally by Kasting et al. (1979) to generate a fractal haze in the model Archean atmosphere. The 1-D line-by-line fully multiple scattering Spectral Mapping Atmospheric Radiative Transfer Model (SMART) (Meadows and Crisp 1996) is then used to generate synthetic spectra of early Earth with haze. We find (Fig 1) that haze scattering significantly depletes the radiation at short wavelengths, strongly affecting the spectral region of the Rayleigh slope, a broadband change in spectral shape detectable at low spectral resolution. At the surface, the spectral energy distribution is shifted towards longer wavelengths, which may be important to photosynthetic life. Thus, the haze may have significant effects on biology, which in turn produces the methane that leads to haze formation, creating feedback loops between biology and the planet.

  8. Pulse-assisted homonuclear dipolar recoupling of half-integer quadrupolar spins in magic-angle spinning NMR

    NASA Astrophysics Data System (ADS)

    Edén, Mattias; Annersten, Hans; Zazzi, Åsa

    2005-07-01

    We demonstrate numerically and experimentally that zero-quantum homonuclear dipolar recoupling techniques employing rotor-synchronized 180° pulses, previously introduced for spin-1/2 applications, are useful also for magnetization transfers between half-integer quadrupolar nuclei in rotating solids. The recoupling sequences are incorporated as mixing periods in two-dimensional experimental protocols, that correlate either single-quantum coherences of coupled spins, or triple-quantum with single-quantum coherences for improving spectral resolution. We present 23Na and 27Al NMR experiments on powders of sodium sulphite [Na 2SO 3], YAG [Y 3Al 5O 12] and a synthetic chlorite mineral [Mg 4.5Al 3Si 2.5O 10(OH) 8].

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

    PubMed

    D'Amelio, Nicola; Gaggelli, Elena; Molteni, Elena; Valensin, Gianni

    2005-01-01

    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 or to give a physical interpretation of experimental results. The program allows to independently follow the dependence of individual coherences and relaxation rates as a function of up to 50 parameters regarding the physical properties of the system under investigation, sample conditions and instrumental setup making it an helpful tool also for teaching purposes.

  10. ON THE EFFECTS OF THE EVOLUTION OF MICROBIAL MATS AND LAND PLANTS ON THE EARTH AS A PLANET. PHOTOMETRIC AND SPECTROSCOPIC LIGHT CURVES OF PALEO-EARTHS

    SciTech Connect

    Sanroma, E.; Palle, E.; Garcia Munoz, A.

    2013-04-01

    Understanding the spectral and photometric variability of the Earth and the rest of the solar system planets has become of utmost importance for the future characterization of rocky exoplanets. As this is not only interesting at present times but also along the planetary evolution, we studied the effect that the evolution of microbial mats and plants over land has had on the way our planet looks from afar. As life evolved, continental surfaces changed gradually and non-uniformly from deserts through microbial mats to land plants, modifying the reflective properties of the ground and most likely the distribution of moisture and cloudiness. Here, we used a radiative transfer model of the Earth, together with geological paleo-records of the continental distribution and a reconstructed cloud distribution, to simulate the visible and near-IR radiation reflected by our planet as a function of Earth's rotation. We found that the evolution from deserts to microbial mats and to land plants produces detectable changes in the globally averaged Earth's reflectance. The variability of each surface type is located in different bands and can induce reflectance changes of up to 40% in period of hours. We conclude that by using photometric observations of an Earth-like planet at different photometric bands it would be possible to discriminate between different surface types. While recent literature proposes the red-edge feature of vegetation near 0.7 {mu}m as a signature for land plants, observations in near-IR bands can be equally or even better suited for this purpose.

  11. On the Effects of the Evolution of Microbial Mats and Land Plants on the Earth as a Planet. Photometric and Spectroscopic Light Curves of Paleo-Earths

    NASA Astrophysics Data System (ADS)

    Sanromá, E.; Pallé, E.; García Munõz, A.

    2013-04-01

    Understanding the spectral and photometric variability of the Earth and the rest of the solar system planets has become of utmost importance for the future characterization of rocky exoplanets. As this is not only interesting at present times but also along the planetary evolution, we studied the effect that the evolution of microbial mats and plants over land has had on the way our planet looks from afar. As life evolved, continental surfaces changed gradually and non-uniformly from deserts through microbial mats to land plants, modifying the reflective properties of the ground and most likely the distribution of moisture and cloudiness. Here, we used a radiative transfer model of the Earth, together with geological paleo-records of the continental distribution and a reconstructed cloud distribution, to simulate the visible and near-IR radiation reflected by our planet as a function of Earth's rotation. We found that the evolution from deserts to microbial mats and to land plants produces detectable changes in the globally averaged Earth's reflectance. The variability of each surface type is located in different bands and can induce reflectance changes of up to 40% in period of hours. We conclude that by using photometric observations of an Earth-like planet at different photometric bands it would be possible to discriminate between different surface types. While recent literature proposes the red-edge feature of vegetation near 0.7 μm as a signature for land plants, observations in near-IR bands can be equally or even better suited for this purpose.

  12. Possible effects on Earth's climate due to reduced atmospheric ionization by GCR during Forbush Decreases

    NASA Astrophysics Data System (ADS)

    Portugal, Williamary; Echer, Ezequiel; Pereira de Souza Echer, Mariza; Pacini, Alessandra Abe

    2017-10-01

    This work presents the first results of a study about possible effects on the surface temperature during short periods of lower fluxes of Galactic Cosmic Rays at Earth, called Forbush Decreases. There is a hypothesis that the Galactic Cosmic Ray flux decreases cause changes on the physical-chemical properties of the atmosphere. We have conducted a study to investigate these possible effects on several latitudinal regions, around the ten strongest FDs occurred from 1987 to 2015. We have found a possible increase on the surface temperature at middle and high latitudes during the occurence of these events.

  13. Test of general relativity and measurement of the lense-thirring effect with two earth satellites

    PubMed

    Ciufolini; Pavlis; Chieppa; Fernandes-Vieira; Perez-Mercader

    1998-03-27

    The Lense-Thirring effect, a tiny perturbation of the orbit of a particle caused by the spin of the attracting body, was accurately measured with the use of the data of two laser-ranged satellites, LAGEOS and LAGEOS II, and the Earth gravitational model EGM-96. The parameter &mgr;, which measures the strength of the Lense-Thirring effect, was found to be 1.1 +/- 0.2; general relativity predicts &mgr; identical with 1. This result represents an accurate test and measurement of one of the fundamental predictions of general relativity, that the spin of a body changes the geometry of the universe by generating space-time curvature.

  14. Effects on optical systems from interactions with oxygen atoms in low earth orbits

    NASA Technical Reports Server (NTRS)

    Peters, P. N.; Swann, J. T.; Gregory, J. C.

    1986-01-01

    Modifications of material surface properties due to interactions with ambient atomic oxygen have been observed on surfaces facing the orbital direction in low earth orbits. Some effects are very damaging to surface optical properties while some are more subtle and even beneficial. Most combustible materials are heavily etched, and some coatings, such as silver and osmium, are seriously degraded or removed as volatile oxides. The growth of oxide films on metals and semiconductors considered stable in dry air was measured. Material removal, surface roughness, reflectance, and optical densities are reported. Effects of temperature, contamination, and overcoatings are noted.

  15. Solar and terrestrial physics. [effects of solar activities on earth environment

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The effects of solar radiation on the near space and biomental earth, the upper atmosphere, and the magnetosphere are discussed. Data obtained from the OSO satellites pertaining to the solar cycle variation of extreme ultraviolet (EUV) radiation are analyzed. The effects of solar cycle variation of the characteristics of the solar wind are examined. The fluid mechanics of shock waves and the specific relationship to the characteristics of solar shock waves are investigated. The solar and corpuscular heating of the upper atmosphere is reported based on the findings of the AEROS and NATE experiments. Seasonal variations of the upper atmosphere composition are plotted based on OGO-6 mass spectrometer data.

  16. Empirical determination of the effects of clouds on the Earth's Radiation Budget over the Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Ziskin, Daniel; Strobel, Darrell F.

    1992-01-01

    The main objectives of this research has been to learn how clouds interact with the Earth's Radiation Budget (ERB). This broad goal has been approached in three distinct ways. The first has been to analyze the direct effect cloud amount has on the radiative components of the ERB. The second has been to investigate the indirect effects clouds and water vapor may have on the climate as a feedback mechanism. And finally an attempt has been made to simulate the findings in a simple radiative-convective climate model. This report will summarize these three phases of the research.

  17. Displacements of the earth's surface due to atmospheric loading - Effects of gravity and baseline measurements

    NASA Technical Reports Server (NTRS)

    Van Dam, T. M.; Wahr, J. M.

    1987-01-01

    Atmospheric mass loads and deforms the earth's crust. By performing a convolution sum between daily, global barometric pressure data and mass loading Green's functions, the time dependent effects of atmospheric loading, including those associated with short-term synoptic storms, on surface point positioning measurements and surface gravity observations are estimated. The response for both an oceanless earth and an earth with an inverted barometer ocean is calculated. Load responses for near-coastal stations are significantly affected by the inclusion of an inverted barometer ocean. Peak-to-peak vertical displacements are frequently 15-20 mm with accompanying gravity perturbations of 3-6 micro Gal. Baseline changes can be as large as 20 mm or more. The perturbations are largest at higher latitudes and during winter months. These amplitudes are consistent with the results of Rabbel and Zschau (1985), who modeled synoptic pressure disturbances as Gaussian functions of radius around a central point. Deformation can be adequately computed using real pressure data from points within about 1000 km of the station. Knowledge of local pressure, alone, is not sufficient. Rabbel and Zschau's hypothesized corrections for these displacements, which use local pressure and the regionally averaged pressure, prove accurate at points well inland but are, in general, inadequate within a few hundred kilometers of the coast.

  18. Displacements of the earth's surface due to atmospheric loading - Effects of gravity and baseline measurements

    NASA Technical Reports Server (NTRS)

    Van Dam, T. M.; Wahr, J. M.

    1987-01-01

    Atmospheric mass loads and deforms the earth's crust. By performing a convolution sum between daily, global barometric pressure data and mass loading Green's functions, the time dependent effects of atmospheric loading, including those associated with short-term synoptic storms, on surface point positioning measurements and surface gravity observations are estimated. The response for both an oceanless earth and an earth with an inverted barometer ocean is calculated. Load responses for near-coastal stations are significantly affected by the inclusion of an inverted barometer ocean. Peak-to-peak vertical displacements are frequently 15-20 mm with accompanying gravity perturbations of 3-6 micro Gal. Baseline changes can be as large as 20 mm or more. The perturbations are largest at higher latitudes and during winter months. These amplitudes are consistent with the results of Rabbel and Zschau (1985), who modeled synoptic pressure disturbances as Gaussian functions of radius around a central point. Deformation can be adequately computed using real pressure data from points within about 1000 km of the station. Knowledge of local pressure, alone, is not sufficient. Rabbel and Zschau's hypothesized corrections for these displacements, which use local pressure and the regionally averaged pressure, prove accurate at points well inland but are, in general, inadequate within a few hundred kilometers of the coast.

  19. High-Accuracy Ring Laser Gyroscopes: Earth Rotation Rate and Relativistic Effects

    NASA Astrophysics Data System (ADS)

    Beverini, N.; Di Virgilio, A.; Belfi, J.; Ortolan, A.; Schreiber, K. U.; Gebauer, A.; Klügel, T.

    2016-06-01

    The Gross Ring G is a square ring laser gyroscope, built as a monolithic Zerodur structure with 4 m length on all sides. It has demonstrated that a large ring laser provides a sensitivity high enough to measure the rotational rate of the Earth with a high precision of ΔΩE < 10-8. It is possible to show that further improvement in accuracy could allow the observation of the metric frame dragging, produced by the Earth rotating mass (Lense-Thirring effect), as predicted by General Relativity. Furthermore, it can provide a local measurement of the Earth rotational rate with a sensitivity near to that provided by the international system IERS. The GINGER project is intending to take this level of sensitivity further and to improve the accuracy and the long-term stability. A monolithic structure similar to the G ring laser is not available for GINGER. Therefore the preliminary goal is the demonstration of the feasibility of a larger gyroscope structure, where the mechanical stability is obtained through an active control of the geometry. A prototype moderate size gyroscope (GP-2) has been set up in Pisa in order to test this active control of the ring geometry, while a second structure (GINGERino) has been installed inside the Gran Sasso underground laboratory in order to investigate the properties of a deep underground laboratory in view of an installation of a future GINGER apparatus. The preliminary data on these two latter instruments are presented.

  20. Diatomaceous earth and oil enhance effectiveness of Metarhizium anisopliae against Triatoma infestans.

    PubMed

    Luz, Christian; Rodrigues, Juscelino; Rocha, Luiz F N

    2012-04-01

    Entomopathogenic fungi, especially Metarhizium anisopliae, have potential for integrated control of peridomestic triatomine bugs. However, the high susceptibility of these vectors to fungal infection at elevated ambient humidities decreases in the comparatively dry conditions that often prevail in their microhabitats. A formulation adapted to this target pest that induces high and quick mortality can help to overcome these drawbacks. In the present study diatomaceous earth, which is used against pests of stored grains or as an additive to mycoinsecticides, delayed but did not reduce in vitro germination of M. anisopliae s.l. IP 46 conidia after >24h agitation without affecting viability, and did not hamper the survival of Triatoma infestans nymphs exposed to treated surfaces. The settling behavior of nymphs on a treated surface in choice tests depended on the concentration of diatomaceous earth and ambient light level. Conidia formulated with diatomaceous earth and a vegetable oil synergized the insecticidal effect of the fungus in nymphs, and quickly killed all treated insects, even at 75% relative humidity (LT(90) 8.3 days) where unformulated conidia caused only 25% mortality after a 25 days exposure. The improved performance of a combined oil and desiccant dust formulation of this Metarhizium isolate raises the likelihood for its successful mycoinsecticidal use for triatomine control and, apparently, against other domestic insect pests. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Sunlight effects on the 3D polar current system determined from low Earth orbit measurements

    NASA Astrophysics Data System (ADS)

    Laundal, Karl M.; Finlay, Christopher C.; Olsen, Nils

    2016-08-01

    Interaction between the solar wind and the Earth's magnetosphere is associated with large-scale currents in the ionosphere at polar latitudes that flow along magnetic field lines (Birkeland currents) and horizontally. These current systems are tightly linked, but their global behaviors are rarely analyzed together. In this paper, we present estimates of the average global Birkeland currents and horizontal ionospheric currents from the same set of magnetic field measurements. The magnetic field measurements, from the low Earth orbiting Swarm and CHAMP satellites, are used to co-estimate poloidal and toroidal parts of the magnetic disturbance field, represented in magnetic apex coordinates. The use of apex coordinates reduces effects of longitudinal and hemispheric variations in the Earth's main field. We present global currents from both hemispheres during different sunlight conditions. The results show that the Birkeland currents vary with the conductivity, which depends most strongly on solar EUV emissions on the dayside and on particle precipitation at pre-midnight magnetic local times. In sunlight, the horizontal equivalent current flows in two cells, resembling an opposite ionospheric convection pattern, which implies that it is dominated by Hall currents. By combining the Birkeland current maps and the equivalent current, we are able to calculate the total horizontal current, without any assumptions about the conductivity. We show that the total horizontal current is close to zero in the polar cap when it is dark. That implies that the equivalent current, which is sensed by ground magnetometers, is largely canceled by the horizontal closure of the Birkeland currents.

  2. Uranyl Carbonate Complexes in Aqueous Solution and Their Ligand NMR Chemical Shifts and (17)O Quadrupolar Relaxation Studied by ab Initio Molecular Dynamics.

    PubMed

    Marchenko, Alex; Truflandier, Lionel A; Autschbach, Jochen

    2017-07-03

    Dynamic structural effects, NMR ligand chemical shifts, and (17)O NMR quadrupolar relaxation rates are investigated in the series of complexes UO2(2+), UO2(CO3)3(4-), and (UO2)3(CO3)6(6-). Car-Parrinello molecular dynamics (CPMD) is used to simulate the dynamics of the complexes in water. NMR properties are computed on clusters extracted from the CPMD trajectories. In the UO2(2+) complex, coordination at the uranium center by water molecules causes a decrease of around 300 ppm for the uranyl (17)O chemical shift. The final value of this chemical shift is within 40 ppm of the experimental range. The UO2(CO3)3(4-) and (UO2)3(CO3)6(6-) complexes show a solvent dependence of the terminal carbonate (17)O and (13)C chemical shifts that is less pronounced than that for the uranyl oxygen atom. Corrections to the chemical shift from hybrid functionals and spin-orbit coupling improve the accuracy of chemical shifts if the sensitivity of the uranyl chemical shift to the uranyl bond length (estimated at 140 ppm per 0.1 Å from trajectory data) is taken into consideration. The experimentally reported trend in the two unique (13)C chemical shifts is correctly reproduced for (UO2)3(CO3)6(6-). NMR relaxation rate data support large (17)O peak widths, but remain below those noted in the experimental literature. Comparison of relaxation data for solvent-including versus solvent-free models suggest that carbonate ligand motion overshadows explicit solvent effects.

  3. Transient magnetic effects in a scale model of the earth's core

    PubMed Central

    Crane, H. R.

    1977-01-01

    Scale model experiments are described in which the contribution to the dipole magnetic field of a conducting sphere (simulating the earth's core) by initially closed, internal flux loops is measured. A magnetic loop is maintained by constant current in a toroidal coil, in a mercury sphere. The circuit is then opened, which allows the magnetic loop to diffuse and dissipate. The time development of the magnetic effects outside the sphere is recorded, especially the contribution in the dipole mode of the sphere. In a sample application of the result, a doughnut-shaped flux loop, of major and minor radii 0.17 and 0.053 Rc (Rc = earth's core radius) and centered at 0.68 Rc, of field strength 100 gauss, in optimal orientation and in a core of conductivity 3 × 10-6 emu is assumed. If one such flux loop is set free on the average of every 40 years, the earth's dipole field is maintained. The relative intensity of the short-lived nondipole component that would accompany the process in the simplified example is estimated from the data and found not to be inconsistent with that observed in the real earth. Only the basic process of the feeding of a poloidal field by initially closed free flux loops in a static conducting sphere is investigated. The requirement that, in a real situation, the loops would have to be set free in a preferred orientation is discussed, and an existing model of a system that in some degree answers the requirement is cited. Images PMID:16592464

  4. Earth Science

    NASA Image and Video Library

    1991-01-01

    In July 1990, the Marshall Space Flight Center, in a joint project with the Department of Defense/Air Force Space Test Program, launched the Combined Release and Radiation Effects Satellite (CRRES) using an Atlas I launch vehicle. The mission was designed to study the effects of artificial ion clouds produced by chemical releases on the Earth's ionosphere and magnetosphere, and to monitor the effects of space radiation environment on sophisticated electronics.

  5. The influence of earth tides on earth's coordinates

    NASA Technical Reports Server (NTRS)

    Vincente, R. O.

    1978-01-01

    The importance of the Earth's tides on Earth coordinates were examined for the following reasons: (1) the precision for obtaining the Earth's coordinates shows that the effects of Earth tides appear on the values obtained for the coordinates; (2) the possibility of determining the values of the Earth tides; and (3) the consideration of theoretical models that can compute the values of Earth tides. The astronomical and geodetic coordinates of a point at the Earth's surface are described.

  6. The effect of a nonuniform planetary albedo on the interpretation of earth radiation budget observations

    NASA Technical Reports Server (NTRS)

    King, M. D.; Curran, R. J.

    1980-01-01

    The flux density measured at satellite altitude with a fixed field of view radiometer differs from the true flux density reflected by the earth-atmosphere system within the field of view of the radiometer. This difference is due to angular response characteristics of the radiometer, solid angle effects due to geometry, and angular reflectance effects of the earth-atmosphere system. All of these effects lead to uncertainties in the interpretation of instantaneous earth radiation budget measurements. The differences between the true flux density and the measured flux density are shown to be significant when the field of view of the radiometer is large and when the atmosphere has a nonuniform, or spatially dependent, reflectance (albedo). A simulation experiment is described whereby the scene within the field of view of a nadir looking sensor is divided into a large number of equal area elements, each of which reflects radiation with one of two different reflectance models (corresponding to cloud-free and cloudy areas). The conditional mean values of the measured flux density, given values of the true flux density, are shown to differ significantly from the conditional means of the inverse problem, that of finding the mean value of the true flux density given a value for the measured flux density. The differences between the true flux density and the measured flux density are examined as a function of satellite altitude, field of view of the radiometer and solar zenith angle (including the effects of a terminator within the field of view) for both Lambertian and non-Lambertian reflectance models.

  7. The Effect of Alkaline Earth Metal on the Cesium Loading of Ionsiv(R) IE-910 and IE-911

    SciTech Connect

    Fondeur, F.F.

    2001-01-16

    This study investigated the effect of variances in alkaline earth metal concentrations on cesium loading of IONSIV(R) IE-911. The study focused on Savannah River Site (SRS) ''average'' solution with varying amounts of calcium, barium and magnesium.

  8. Truncation Effects in Computing Free Wobble/Nutation Modes Explored Using a Simple Earth Model

    NASA Astrophysics Data System (ADS)

    Seyed-Mahmoud, B.; Rochester, M. G.; Rogers, C. M.

    2016-12-01

    The displacement field accompanying the wobble/nutation of the Earth is conventionally represented by an infinite chain of toroidal and spheroidal vector spherical harmonics, coupled by rotation and ellipticity. Numerical solutions for the eigenperiods require truncation of that chain, and the standard approaches using the linear momentum description (LMD) of deformation during wobble/nutation have truncated it at very low degrees, usually degree 3 or 4, and at most degree 5. The effects of such heavy truncation on the computed eigenperiods have hardly been examined. We here investigate the truncation effects on the periods of the free wobble/nutation modes using a simplified Earth model consisting of a homogeneous incompressible inviscid liquid outer core with a rigid (but not fixed) inner core and mantle. A novel Galerkin method is implemented using a Clairaut coordinate system to solve the classic Poincare problem in the liquid core and, to close the problem, we use the Lagrangean formulation of the Liouville equation for each of the solid parts of the Earth model. We find that, except for the free inner core nutation (FICN), the periods of the free rotational modes converge rather quickly. The period of the tiltover mode (TOM) is found to excellent accuracy. The computed periods of the Chandler wobble (CW) and free core nutation (FCN) are nearly identical to the values cited in the literature for similar Earth models, but that for the inner core wobble (ICW) is slightly different. Truncation at low-degree harmonics causes the FICN period to fluctuate over a range as large as 90 sd, with different values at different truncation levels. For example, truncation at degree 6 gives a period of 752 sd (almost identical with the value cited in the literature for such an Earth model) but truncation at degree 24 is required to obtain convergence, and the resulting period is 746 sd, with no guarantee that its proximity to earlier values is other than fortuitous. We

  9. Truncation effects in computing free wobble/nutation modes explored using a simple Earth model

    NASA Astrophysics Data System (ADS)

    Seyed-Mahmoud, Behnam; Rochester, Michael G.; Rogers, Christopher M.

    2017-03-01

    The displacement field accompanying the wobble/nutation of the Earth is conventionally represented by an infinite chain of toroidal and spheroidal vector spherical harmonics, coupled by rotation and ellipticity. Numerical solutions for the eigenperiods require truncation of that chain, and the standard approaches using the linear momentum description (LMD) of deformation during wobble/nutation have truncated it at very low degrees, usually degree 3 or 4, and at most degree 5. The effects of such heavy truncation on the computed eigenperiods have hardly been examined. We here investigate the truncation effects on the periods of the free wobble/nutation modes using a simplified Earth model consisting of a homogeneous incompressible inviscid liquid outer core with a rigid (but not fixed) inner core and mantle. A novel Galerkin method is implemented using a Clairaut coordinate system to solve the classic Poincaré problem in the liquid core and, to close the problem, we use the Lagrangean formulation of the Liouville equation for each of the solid parts of the Earth model. We find that, except for the free inner core nutation (FICN), the periods of the free rotational modes converge rather quickly. The period of the tiltover mode (TOM) is found to excellent accuracy. The computed periods of the Chandler wobble (CW) and free core nutation (FCN) are nearly identical to the values cited in the literature for similar Earth models, but that for the inner core wobble (ICW) is slightly different. Truncation at low-degree harmonics causes the FICN period to fluctuate over a range as large as 90 sd, with different values at different truncation levels. For example, truncation at degree 6 gives a period of 752 sd (almost identical with the value cited in the literature for such an Earth model) but truncation at degree 24 is required to obtain convergence, and the resulting period is 746 ± 1 sd, as more terms are included, with no guarantee that its proximity to earlier values

  10. Truncation effects in computing free wobble/nutation modes explored using a simple Earth model

    NASA Astrophysics Data System (ADS)

    Seyed-Mahmoud, Behnam; Rochester, Michael G.; Rogers, Christopher M.

    2017-06-01

    The displacement field accompanying the wobble/nutation of the Earth is conventionally represented by an infinite chain of toroidal and spheroidal vector spherical harmonics, coupled by rotation and ellipticity. Numerical solutions for the eigenperiods require truncation of that chain, and the standard approaches using the linear momentum description (LMD) of deformation during wobble/nutation have truncated it at very low degrees, usually degree 3 or 4, and at most degree 5. The effects of such heavy truncation on the computed eigenperiods have hardly been examined. We here investigate the truncation effects on the periods of the free wobble/nutation modes using a simplified Earth model consisting of a homogeneous incompressible inviscid liquid outer core with a rigid (but not fixed) inner core and mantle. A novel Galerkin method is implemented using a Clairaut coordinate system to solve the classic Poincaré problem in the liquid core and, to close the problem, we use the Lagrangean formulation of the Liouville equation for each of the solid parts of the Earth model. We find that, except for the free inner core nutation (FICN), the periods of the free rotational modes converge rather quickly. The period of the tiltover mode is found to excellent accuracy. The computed periods of the Chandler wobble and free core nutation are nearly identical to the values cited in the literature for similar Earth models, but that for the inner core wobble is slightly different. Truncation at low-degree harmonics causes the FICN period to fluctuate over a range as large as 90 sd, with different values at different truncation levels. For example, truncation at degree 6 gives a period of 752 sd (almost identical with the value cited in the literature for such an Earth model) but truncation at degree 24 is required to obtain convergence, and the resulting period is 746 ± 1 sd, as more terms are included, with no guarantee that its proximity to earlier values is other than fortuitous

  11. Necessity of using heterogeneous ellipsoidal Earth model with terrain to calculate co-seismic effect

    NASA Astrophysics Data System (ADS)

    Cheng, Huihong; Zhang, Bei; Zhang, Huai; Huang, Luyuan; Qu, Wulin; Shi, Yaolin

    2016-04-01

    Co-seismic deformation and stress changes, which reflect the elasticity of the earth, are very important in the earthquake dynamics, and also to other issues, such as the evaluation of the seismic risk, fracture process and triggering of earthquake. Lots of scholars have researched the dislocation theory and co-seismic deformation and obtained the half-space homogeneous model, half-space stratified model, spherical stratified model, and so on. Especially, models of Okada (1992) and Wang (2003, 2006) are widely applied in the research of calculating co-seismic and post-seismic effects. However, since both semi-infinite space model and layered model do not take the role of the earth curvature or heterogeneity or topography into consideration, there are large errors in calculating the co-seismic displacement of a great earthquake in its impacted area. Meanwhile, the computational methods of calculating the co-seismic strain and stress are different between spherical model and plane model. Here, we adopted the finite element method which could well deal with the complex characteristics (such as anisotropy, discontinuities) of rock and different conditions. We use the mash adaptive technique to automatically encrypt the mesh at the fault and adopt the equivalent volume force replace the dislocation source, which can avoid the difficulty in handling discontinuity surface with conventional (Zhang et al., 2015). We constructed an earth model that included earth's layered structure and curvature, the upper boundary was set as a free surface and the core-mantle boundary was set under buoyancy forces. Firstly, based on the precision requirement, we take a testing model - - a strike-slip fault (the length of fault is 500km and the width is 50km, and the slippage is 10m) for example. Because of the curvature of the Earth, some errors certainly occur in plane coordinates just as previous studies (Dong et al., 2014; Sun et al., 2012). However, we also found that: 1) the co

  12. Effect of Irregularities in the Earth's Rotation on Relativistic Shifts in Frequency and Time of Earthbound Atomic Clocks

    NASA Astrophysics Data System (ADS)

    Fateev, V. F.; Kopeikin, S. M.; Pasynok, S. L., S. L.

    2015-10-01

    The effect of irregularities in the earth's rotation (precession and nutation of the earth's axis of rotation, oscillations in the modulus of the angular velocity, periodic deviations in the line of the poles, and the angular momentum of the globe) on the frequency and time of high-stability atomic clocks are examined in terms of the theory of relativity. It is shown that the relative shift in frequency and time owing to these effects can exceed 5×10-16.

  13. A Supernova at 50 pc: Effects on the Earth's Atmosphere and Biota

    NASA Astrophysics Data System (ADS)

    Melott, A. L.; Thomas, B. C.; Kachelrieß, M.; Semikoz, D. V.; Overholt, A. C.

    2017-05-01

    Recent 60Fe results have suggested that the estimated distances of supernovae in the last few million years should be reduced from ˜100 to ˜50 pc. Two events or series of events are suggested, one about 2.7 million years to 1.7 million years ago, and another about 6.5-8.7 million years ago. We ask what effects such supernovae are expected to have on the terrestrial atmosphere and biota. Assuming that the Local Bubble was formed before the event being considered, and that the supernova and the Earth were both inside a weak, disordered magnetic field at that time, TeV-PeV cosmic rays (CRs) at Earth will increase by a factor of a few hundred. Tropospheric ionization will increase proportionately, and the overall muon radiation load on terrestrial organisms will increase by a factor of ˜150. All return to pre-burst levels within 10 kyr. In the case of an ordered magnetic field, effects depend strongly on the field orientation. The upper bound in this case is with a largely coherent field aligned along the line of sight to the supernova, in which case, TeV-PeV CR flux increases are ˜104 in the case of a transverse field they are below current levels. We suggest a substantial increase in the extended effects of supernovae on Earth and in the “lethal distance” estimate; though more work is needed. This paper is an explicit follow-up to Thomas et al. We also provide more detail on the computational procedures used in both works.

  14. Loss of Water in Early Earth's Atmosphere and Its Effects on Habitability

    NASA Astrophysics Data System (ADS)

    Airapetian, Vladimir; Glocer, Alex; Khazanov, George

    2015-08-01

    The short wavelength emission from the Sun has a profound impact on the Earth’s atmosphere. High energy photons ionize the atmosphere and produce photoelectrons. This process provides a major contribution to the acceleration of atmospheric ions due to the vertical separation of ions and electrons, and the formation of the resulting ambipolar electric field. Observations and theory suggest that even a relatively small fraction of super-thermal electrons (photoelectrons) produced due to photoionization can drive the ”polar wind” that is responsible for the transport of ionospheric constituents to the Earth’s magnetosphere.The young Sun was a magnetically active star generating powerful radiative output from its chromosphere, transition region and corona which was a few hundred times greater than that observed today. What effects would the photoionization processes due to the X-ray-UV solar flux from early Sun have on the loss of water from the early Earth?We use the Fokker-Plank code coupled with 1D hydrodynamic code to model the effect of intensive short-wavelength (X-rays to UV band) emission from the young Sun (3.8 and 4.4 Ga) on Earth's atmosphere. Our simulations include the photoionization processes of the Earth’s atmosphere forming a population of photoelectrons (E<600 eV), the kinetic effects of their propagation associated and their contribution in ionosphere - magnetosphere energy redistribution. Our coupled simulations show that the ambipolar electric field can drag atmospheric ions of oxygen and hydrogen to the magnetosphere and produce significant mass loss that can affect the loss of water from the early Earth in the first half a billion years. This process became less efficient in the next 0.2-0.3 Ga that could have provided a window of opportunity for origin of life.

  15. Effects of the observed J2 variations on the Earth's precession and nutation

    NASA Astrophysics Data System (ADS)

    Ferrándiz, José M.; Baenas, Tomás; Belda, Santiago

    2016-04-01

    The Earth's oblateness parameter J2 is closely related to the dynamical ellipticity H, which factorizes the main components of the precession and the different nutation terms. In most theoretical approaches to the Earth's rotation, with IAU2000 nutation theory among them, H is assumed to be constant. The precession model IAU2006 supposes H to have a conventional linear variation, based on the J2 time series derived mainly from satellite laser ranging (SLR) data for decades, which gives rise to an additional quadratic term of the precession in longitude and some corrections of the nutation terms. The time evolution of J2 is, however, too complex to be well approximated by a simple linear model. The effect of more general models including periodic terms and closer to the observed time series, although still unable to reproduce a significant part of the signal, has been seldom investigated. In this work we address the problem of deriving the effect of the observed J2 variations without resorting to such simplified models. The Hamiltonian approach to the Earth rotation is extended to allow the McCullagh's term of the potential to depend on a time-varying oblateness. An analytical solution is derived by means of a suitable perturbation method in the case of the time series provided by the Center for Space Research (CSR) of the University of Texas, which results in non-negligible contributions to the precession-nutation angles. The presentation focuses on the main effects on the longitude of the equator; a noticeable non-linear trend is superimposed to the linear main precession term, along with some periodic and decadal variations.

  16. Unusual locations of Earth's bow shock on September 24 - 25, 1987: Mach number effects

    NASA Astrophysics Data System (ADS)

    Cairns, Iver H.; Fairfield, Donald H.; Anderson, Roger R.; Carlton, Victoria E. H.; Paularena, Karolen I.; Lazarus, Alan J.

    1995-01-01

    International Sun Earth Explorer 1 (ISEE 1) and Interplanetary Monitoring Platform 8 (IMP 8) data are used to identify 19 crossings of Earth's bow shock during a 30-hour period following 0000 UT on September 24, 1987. Apparent standoff distances for the shock are calculated for each crossing using two methods and the spacecraft location; one method assumes the average shock shape, while the other assumes a ram pressure-dependent shock shape. The shock's apparent standoff distance, normally approximately 14 R(sub E), is shown to increase from near 10 R(sub E) initially to near 19 R(sub E) during an 8-hour period, followed by an excursion to near 35 R(sub E) (where two IMP 8 shock crossings occur) and an eventual return to values smaller than 19 R(sub E). The Alfven M(sub A) and fast magnetosonic M(sub ms). Mach numbers remain above 2 and the number density above 4/cu cm for almost the entire period. Ram pressure effects produce the initial near-Earth shock location, whereas expansions and contractions of the bow shock due to low Mach number effects account, qualitatively and semiquantitatively, for the timing and existence of almost all the remaining ISEE crossings and both IMP 8 crossings. Significant quantitative differences exist between the apparent standoff distances for the shock crossings and those predicted using the observed plasma parameters and the standard model based on Spreiter et al.'s (1966) gasdynamic equation. These differences can be explained in terms of either a different dependence of the standoff distance on Mach number at low M(sub A) and M(sub ms), or variations in shock shape with M(sub A) and M(sub ms) (becoming increasingly "puffed up" with decreasing M(sub A) and M(sub ms), as expected theoretically), or by a combination of both effects.

  17. Unusual locations of Earth's bow shock on September 24 - 25, 1987: Mach number effects

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.; Fairfield, Donald H.; Anderson, Oger R.; Carlton, Victoria E. H.; Paularena, Karolen I.; Lazarus, Alan J.

    1995-01-01

    International Sun Earth Explorer 1 (ISEE 1) and Interplanetary Monitoring Platform 8 (IMP 8) data are used to identify 19 crossings of Earth's bow shock during a 30-hour period following 0000 UT on September 24, 1987. Apparent standoff distances for the shock are calculated for each crossing using two methods and the spacecraft location; one method assumes the average shock shape, while the other assumes a ram pressure-dependent shock shape. The shock's apparent standoff distance, normally approximately 14 R(sub E), is shown to increase from near 10 R(sub E) initially to near 19 R(sub E) during an 8-hour period, followed by an excursion to near 35 R(sub E) (where two IMP 8 shock crossings occur) and an eventual return to values smaller than 19 R(sub E). The Alfven M(sub A) and fast magnetosonic M(sub ms). Mach numbers remain above 2 and the number density above 4/cu cm for almost the entire period. Ram pressure effects produce the initial near-Earth shock location, whereas expansions and contractions of the bow shock due to low Mach number effects account, qualitatively and semiquantitatively, for the timing and existence of almost all the remaining ISEE crossings and both IMP 8 crossings. Significant quantitative differences exist between the apparent standoff distances for the shock crossings and those predicted using the observed plasma parameters and the standard model based on Spreiter et al.'s (1966) gasdynamic equation. These differences can be explained in terms of either a different dependence of the standoff distance on Mach number at low M(sub A) and M(sub ms), or variations in shock shape with M(sub A) and M(sub ms) (becoming increasingly "puffed up" with decreasing M(sub A) and M(sub ms), as expected theoretically), or by a combination of both effects.

  18. Metal enhanced fluorescence in rare earth doped plasmonic core-shell nanoparticles.

    PubMed

    Derom, S; Berthelot, A; Pillonnet, A; Benamara, O; Jurdyc, A M; Girard, C; Colas des Francs, G

    2013-12-13

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core-shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) is achieved by tuning either the dipolar or the quadrupolar particle resonance to the rare earth ion's excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal-RE energy transfer mechanism is involved.

  19. Effects of clouds on the Earth radiation budget; Seasonal and inter-annual patterns

    NASA Technical Reports Server (NTRS)

    Dhuria, Harbans L.

    1992-01-01

    Seasonal and regional variations of clouds and their effects on the climatological parameters were studied. The climatological parameters surface temperature, solar insulation, short-wave absorbed, long wave emitted, and net radiation were considered. The data of climatological parameters consisted of about 20 parameters of Earth radiation budget and clouds of 2070 target areas which covered the globe. It consisted of daily and monthly averages of each parameter for each target area for the period, Jun. 1979 - May 1980. Cloud forcing and black body temperature at the top of the atmosphere were calculated. Interactions of clouds, cloud forcing, black body temperature, and the climatological parameters were investigated and analyzed.

  20. Effect of a uniform sea-level change on the earth's rotation and gravitational field

    NASA Technical Reports Server (NTRS)

    Chao, B. Fong; O'Connor, William P.

    1988-01-01

    Global water redistriburtion between the oceans, atmosphere and continents causes changes in the earth's rotation and gravitational field. To conserve water mass, the effect of the small uniform change in sea-level must be considered. Explicit formulas are provided for these sea-level corrections to the gravitational Stokes coefficients, polar motion and length of day. In two recent publications, this sea-level correction term for polar motion was given incorrectly. These errors which arose from normalization conventions with the ocean function are corrected.

  1. Effect of a uniform sea-level change on the earth's rotation and gravitational field

    NASA Technical Reports Server (NTRS)

    Chao, B. Fong; O'Connor, William P.

    1988-01-01

    Global water redistriburtion between the oceans, atmosphere and continents causes changes in the earth's rotation and gravitational field. To conserve water mass, the effect of the small uniform change in sea-level must be considered. Explicit formulas are provided for these sea-level corrections to the gravitational Stokes coefficients, polar motion and length of day. In two recent publications, this sea-level correction term for polar motion was given incorrectly. These errors which arose from normalization conventions with the ocean function are corrected.

  2. Cost-effective technology advancement directions for electric propulsion transportation systems in earth-orbital missions

    NASA Technical Reports Server (NTRS)

    Regetz, J. D., Jr.; Terwilliger, C. H.

    1979-01-01

    The directions that electric propulsion technology should take to meet the primary propulsion requirements for earth-orbital missions in the most cost effective manner are determined. The mission set requirements, state of the art electric propulsion technology and the baseline system characterized by it, adequacy of the baseline system to meet the mission set requirements, cost optimum electric propulsion system characteristics for the mission set, and sensitivities of mission costs and design points to system level electric propulsion parameters are discussed. The impact on overall costs than specific masses or costs of propulsion and power systems is evaluated.

  3. Effective and responsible teaching of climate change in Earth Science-related disciplines

    NASA Astrophysics Data System (ADS)

    Robinson, Z. P.; Greenhough, B. J.

    2009-04-01

    topic to cover within the Earth Science-related curricula due to wide-ranging, and sometimes polarised, existing attitudes of students and levels of existing partial and sometimes flawed knowledge in addition to the troublesome concepts that need to be grasped. These issues highlight the responsibility and challenge inherent in teaching the subject of climate change and the importance of consideration of integrating sustainability issues with the core science of climate change. The talk will include a discussion of strategies and resources for the effective teaching of climate change topics for a range of levels and discipline backgrounds.

  4. Controlling the metal insulator transition using the ferroelectric field effect in rare earth nickelates

    NASA Astrophysics Data System (ADS)

    Marshall, Matthew; Disa, Ankit; Kumah, Divine; Chen, Hanghui; Ismail-Beigi, Sohrab; Walker, Fred; Ahn, Charles

    2013-03-01

    A ferroelectric field effect transistor (FE-FET) modulates conductivity in a non-volatile manner by electrostatically accumulating and depleting charge carriers at the interface between a conducting channel and ferroelectric gate. The rare earth nickelate LaNiO3 is metallic in bulk, while other rare earth nickelates, such as NdNiO3, exhibit metal-insulator transitions and anti-ferromagnetic behavior in the bulk. Here, we show that by coupling the ferroelectric polarization of Pb0.8Zr0.2TiO3 (PZT) to the carriers in a nickelate, we can dynamically induce a metal- insulator transition in ultra-thin films of LaNiO3, and induce large changes in the MIT transition temperature in NdNiO3. Density functional theory is used to determine changes in the physical and electronic Ni-O-Ni bond angle of the nickelate at the interface between PZT and LaNiO3. The effect of the ferroelectric polarization is to decrease the Ni-O-Ni bond angle from 180 degrees and increase the carrier effective mass. Related to this change in electronic structure, we observe a change in resistivity of approximately 80% at room temperature for an ultra-thin 3 unit cell thick film of LaNiO3. Work supported by FENA and the NSF under MRSEC DMR 1119826.

  5. The Pale Orange Dot: Spectral Effects of a Hazy Early Earth

    NASA Astrophysics Data System (ADS)

    Arney, G.; Domagal-Goldman, S.; Meadows, V.

    2014-03-01

    Several studies have suggested that the Archean Earth atmosphere had a photochemically generated hydrocarbon haze similar to that of Titan, with important climactic implications for our early planet (Pavlov et al. 2001, Trainer al al. 2006, Haqq-Misra et al. 2008, Domagal-Goldman et al. 2008, Wolf and Toon 2012, Zerkle et al. 2012). Haze forms when the ratio of CH4 to CO2 in the atmosphere reaches ~0.1 (Haqq-Misra et al. 2008), and the resultant hydrocarbon haze can contain fractal particles. Compared to spherical particles, fractal particles produce less antigreenhouse cooling and can act as a UV shield (Wolf and Toon 2012), potentially enhancing the habitability of our young planet. If hazy exoplanets are common, the effects of hazes on planetary spectra will be relevant to future exoplanet spectral characterization missions. Previous studies of the detectability of biosignatures on early Earth (e.g. Kaltenegger et al. 2007) have not incorporated the effect of hazes. We consider the implications of spherical and fractal organic aerosol hazes on the spectrum of Archean Earth, examining in particular the impact of a haze layer in discerning spectral features from H2O, CH4, and other gases that have been suggested as putative biosignatures on anoxic planets such as C2H6 (Domagal-Goldman et al. 2011). We use a modified version of the 1-D photochemical code developed originally by Kasting et al. (1979) to generate a self-consistent haze in the model Archean atmosphere. The 1-D line-by-line fully multiple scattering Spectral Mapping Atmospheric Radiative Transfer Model (SMART) (Meadows and Crisp 1996) is then used to generate synthetic spectra of early Earth with haze. In the thermal IR, haze decreases the effective emitting temperature, so the planet appears colder than its surface temperature would dictate. Haze scattering significantly depletes the radiation at short wavelengths, but at longer visible wavelengths the haze increases the reflectivity making the planet

  6. Propagation effects on radio range and noise in earth-space telecommunications

    NASA Technical Reports Server (NTRS)

    Flock, W. L.; Slobin, S. D.; Smith, E. K.

    1982-01-01

    Attention is given to the propagation effects on radio range and noise in earth-space telecommunications. The use of higher frequencies minimizes ionospheric effects on propagation, but tropospheric effects often increase or dominate. For paths of geostationary satellites, and beyond, the excess range delay caused by the ionosphere and plasmasphere is proportional to the total electron content along the path and inversely proportional to frequency squared. The delay due to dry air is usually of the order of a few meters while the delay due to water vapor (a few tens of centimeters) is responsible for most of the temporal variation in the range delay for clean air. For systems such as that of the Voyager spacecraft, and for attenuation values up to about 10 dB, increased sky noise degrades the received signal-to-noise ratio more than does the reduction in signal level due to attenuation.

  7. Propagation effects on radio range and noise in earth-space telecommunications

    NASA Technical Reports Server (NTRS)

    Flock, W. L.; Slobin, S. D.; Smith, E. K.

    1982-01-01

    Attention is given to the propagation effects on radio range and noise in earth-space telecommunications. The use of higher frequencies minimizes ionospheric effects on propagation, but tropospheric effects often increase or dominate. For paths of geostationary satellites, and beyond, the excess range delay caused by the ionosphere and plasmasphere is proportional to the total electron content along the path and inversely proportional to frequency squared. The delay due to dry air is usually of the order of a few meters while the delay due to water vapor (a few tens of centimeters) is responsible for most of the temporal variation in the range delay for clean air. For systems such as that of the Voyager spacecraft, and for attenuation values up to about 10 dB, increased sky noise degrades the received signal-to-noise ratio more than does the reduction in signal level due to attenuation.

  8. Uptake and effect of rare earth elements on gene expression in Methylosinus trichosporium OB3b

    DOE PAGES

    Gu, Wenyu; Farhan Ul Haque, Muhammad; DiSpirito, Alan A.; ...

    2016-05-12

    It is well-known that M. trichosporium OB3b has two forms of methane monooxygenase responsible for the initial conversion of methane to methanol, a cytoplasmic (soluble) methane monooxygenase (sMMO) and a membrane-associated (particulate) methane monooxygenase (pMMO) and that copper strongly regulates expression of these alternative forms of MMO. More recently, it has been discovered that M. trichosporium OB3b has multiple types of the methanol dehydrogenase (MeDH), i.e. the Mxa-MeDH and Xox-MeDH, and the expression of these two forms is regulated by the availability of the rare earth element, cerium. Here we extend these studies and show that lanthanum, praseodymium, neodymium andmore » samarium also regulate expression of alternative forms of MeDH. The effect of these rare earth elements on MeDH expression, however, was only observed in the absence of copper. Further, a mutant of M. trichosporium OB3b where the Mxa-MeDH was knocked out was able to grow in the presence of lanthanum, praseodymium and neodymium, but was not able to grow in the presence of samarium. In conclusion, collectively these data suggest that multiple levels of gene regulation by metals exist in M. trichosporium OB3b but that copper overrides the effect of other metals by an as yet unknown mechanism.« less

  9. Effects of rare-earth filters on patient exposure and image contrast

    SciTech Connect

    Mauriello, S.M.; Washburn, D.B.; Matteson, S.R.

    1987-08-01

    Minimizing patient exposure while maintaining a diagnostically acceptable radiograph is a major goal in diagnostic radiography. Rare-earth filters may be the means to achieve this goal due to their band-pass effect. The purpose of this study was to examine the image contrast effects and exposure reductions for various thicknesses of aluminum, samarium, gadolinium, gadolinium oxysulfide, and gadolinium oxysulfide added to 2.5 mm of aluminum. Trials were conducted on an intra-oral dental x-ray unit (range, 65 to 90 kVp). When compared with conventional aluminum, all of the rare-earth filters provided lower radiation exposures, with gadolinium in the metallic or oxysulfide form providing the lowest exposures. Samarium, at a thickness of 0.127 mm, yielded the highest image contrast. Gadolinium or gadolinium oxysulfide added to 2.5 mm of aluminum resulted in a slight loss of contrast when compared with conventional aluminum filtration. This loss may not be clinically significant, and when coupled with the reduced exposure afforded by these filters, they become viable as acceptable alternatives to aluminum filtration.

  10. Near-Earth Magnetic Field Effects of Large-Scale Magnetospheric Currents

    NASA Astrophysics Data System (ADS)

    Lühr, Hermann; Xiong, Chao; Olsen, Nils; Le, Guan

    2017-03-01

    Magnetospheric currents play an important role in the electrodynamics of near-Earth space. This has been the topic of many space science studies. Here we focus on the magnetic fields they cause close to Earth. Their contribution to the geomagnetic field is the second largest after the core field. Significant progress in interpreting the magnetic fields from the different sources has been achieved thanks to magnetic satellite missions like Ørsted, CHAMP and now Swarm. Of particular interest for this article is a proper representation of the magnetospheric ring current effect. Uncertainties in modelling its effect still produce the largest residuals between observations and present-day geomagnetic field models. A lot of progress has been achieved so far, but there are still open issues like the characteristics of the partial ring current. Other currents discussed are those flowing in the magnetospheric tail. Also their magnetic contribution at LEO orbits is non-negligible. Treating them as an independent source is a more recent development, which has cured some of the problems in geomagnetic field modelling. Unfortunately there is no index available for characterising the tail current intensity. Here we propose an approach that may help to properly quantify the magnetic contribution from the tail current for geomagnetic field modelling. Some open questions that require further investigation are mentioned at the end.

  11. Near-Earth Magnetic Field Effects of Large-Scale Magnetospheric Currents

    NASA Technical Reports Server (NTRS)

    Luehr, Hermann; Xiong, Chao; Olsen, Nils; Le, Guan

    2016-01-01

    Magnetospheric currents play an important role in the electrodynamics of near- Earth space. This has been the topic of many space science studies. Here we focus on the magnetic fields they cause close to Earth. Their contribution to the geomagnetic field is the second largest after the core field. Significant progress in interpreting the magnetic fields from the different sources has been achieved thanks to magnetic satellite missions like Ørsted, CHAMP and now Swarm. Of particular interest for this article is a proper representation of the magnetospheric ring current effect. Uncertainties in modelling its effect still produce the largest residuals between observations and present-day geomagnetic field models. A lot of progress has been achieved so far, but there are still open issues like the characteristics of the partial ring current. Other currents discussed are those flowing in the magnetospheric tail. Also their magnetic contribution at LEO orbits is non-negligible. Treating them as an independent source is a more recent development, which has cured some of the problems in geomagnetic field modelling. Unfortunately there is no index available for characterizing the tail current intensity. Here we propose an approach that may help to properly quantify the magnetic contribution from the tail current for geomagnetic field modelling. Some open questions that require further investigation are mentioned at the end.

  12. On the effect of ocean tides and tesseral harmonics on spacecraft flybys of the Earth

    NASA Astrophysics Data System (ADS)

    Acedo, L.

    2016-12-01

    The so-called flyby anomaly has encouraged several authors to analyse in detail the minor perturbative contributions to the trajectory of spacecraft performing a flyby manoeuvre. This anomaly consist of an unexplained increase or decrease of the asymptotic velocity of the spacecraft after a flyby of the Earth in the range of a few mm per second. Some order of magnitude estimations have been performed in recent years to dismiss many possible conventional effects as the source of such an anomaly but no explanation has been found yet. In this paper we perform a study of the perturbation induced by ocean tides in a flybying spacecraft by considering the time dependence of the location of the high tide as the Moon follows its orbit. We show that this effect implies a change of the spacecraft velocity of a few micrometres per second. We also consider the coupling of tesseral harmonics inhomogeneities and the rotation of the Earth and its impact on the spacecraft outgoing velocity. Significant corrections to the observed asymptotic velocities are found in this case but neither their sign nor their magnitude coincide with the anomalies. So, we can also rule this out as a conventional explanation.

  13. Near-Earth Magnetic Field Effects of Large-Scale Magnetospheric Currents

    NASA Technical Reports Server (NTRS)

    Luehr, Hermann; Xiong, Chao; Olsen, Nils; Le, Guan

    2016-01-01

    Magnetospheric currents play an important role in the electrodynamics of near- Earth space. This has been the topic of many space science studies. Here we focus on the magnetic fields they cause close to Earth. Their contribution to the geomagnetic field is the second largest after the core field. Significant progress in interpreting the magnetic fields from the different sources has been achieved thanks to magnetic satellite missions like Ørsted, CHAMP and now Swarm. Of particular interest for this article is a proper representation of the magnetospheric ring current effect. Uncertainties in modelling its effect still produce the largest residuals between observations and present-day geomagnetic field models. A lot of progress has been achieved so far, but there are still open issues like the characteristics of the partial ring current. Other currents discussed are those flowing in the magnetospheric tail. Also their magnetic contribution at LEO orbits is non-negligible. Treating them as an independent source is a more recent development, which has cured some of the problems in geomagnetic field modelling. Unfortunately there is no index available for characterizing the tail current intensity. Here we propose an approach that may help to properly quantify the magnetic contribution from the tail current for geomagnetic field modelling. Some open questions that require further investigation are mentioned at the end.

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

    NASA Astrophysics Data System (ADS)

    Schulz, M.

    2008-05-01

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

  15. Effective Integration of the World-Wide Web in Earth Science Education.

    ERIC Educational Resources Information Center

    Herbert, Bruce; Bednarz, Sarah; Boyd, Tom; Blake, Sally; Harder, Vicki; Sutter, Marilyn

    The earth sciences is an evolving set of disciplines encompassing more than 30 specialties; however, earth scientists continue to be trained within the traditional disciplinary structure. Earth science education should focus not only on student acquisition and retention of factual knowledge, but also on the development of higher-order skills…

  16. The effect of the Earth's oblateness on the Moon's physical libration in latitude

    NASA Astrophysics Data System (ADS)

    Kondratyev, B. P.

    2013-05-01

    The Moon's physical libration in latitude generated by gravitational forces caused by the Earth's oblateness has been examined by a vector analytical method. Libration oscillations are described by a close set of five linear inhomogeneous differential equations, the dispersion equation has five roots, one of which is zero. A complete solution is obtained. It is revealed that the Earth's oblateness: a) has little effect on the instantaneous axis of Moon's rotation, but causes an oscillatory rotation of the body of the Moon with an amplitude of 0.072″ and pulsation period of 16.88 Julian years; b) causes small nutations of poles of the orbit and of the ecliptic along tight spirals, which occupy a disk with a cut in a center and with radius of 0.072″. Perturbations caused by the spherical Earth generate: a) physical librations in latitude with an amplitude of 34.275″; b) nutational motion for centers of small spiral nutations of orbit (ecliptic) pole over ellipses with semi-major axes of 113.850″ (85.158″) and the first pole rotates round the second one along a circle with radius of 28.691″; c) nutation of the Moon's celestial pole over an ellipse with a semi-major axis of 45.04″ and with an axes ratio of about 0.004 with a period of T = 27.212 days. The principal ellipse's axis is directed tangentially with respect to the precession circumference, along which the celestial pole moves nonuniformly nearly in one dimension. In contrast to the accepted concept, the latitude does not change while the Moon's poles of rotation move. The dynamical reason for the inclination of the Moon's mean equator with respect to the ecliptic is oblateness of the body of the Moon.

  17. Quantum effects on Lagrangian points and displaced periodic orbits in the Earth-Moon system

    NASA Astrophysics Data System (ADS)

    Battista, Emmanuele; Dell'Agnello, Simone; Esposito, Giampiero; Simo, Jules

    2015-04-01

    Recent work in the literature has shown that the one-loop long distance quantum corrections to the Newtonian potential imply tiny but observable effects in the restricted three-body problem of celestial mechanics; i.e., at the Lagrangian libration points of stable equilibrium, the planetoid is not exactly at an equal distance from the two bodies of large mass, but the Newtonian values of its coordinates are changed by a few millimeters in the Earth-Moon system. First, we assess such a theoretical calculation by exploiting the full theory of the quintic equation, i.e., its reduction to Bring-Jerrard form and the resulting expression of roots in terms of generalized hypergeometric functions. By performing the numerical analysis of the exact formulas for the roots, we confirm and slightly improve the theoretical evaluation of quantum corrected coordinates of Lagrangian libration points of stable equilibrium. Second, we prove in detail that for collinear Lagrangian points the quantum corrections are also of the same order of magnitude in the Earth-Moon system. Third, we discuss the prospects of measuring, with the help of laser ranging, the above departure from the equilateral triangle picture, which is a challenging task. On the other hand, a modern version of the planetoid is the solar sail, and much progress has been made, in recent years, on the displaced periodic orbits of solar sails at all libration points, both stable and unstable. Therefore, the present paper investigates, eventually, a restricted three-body problem involving Earth, the Moon, and a solar sail. By taking into account the one-loop quantum corrections to the Newtonian potential, displaced periodic orbits of the solar sail at libration points are again found to exist.

  18. Quadrupolar and dipolar contributions to x-ray magnetic circular dichroism at the Tb L3,2 edges: Experiment versus theory

    NASA Astrophysics Data System (ADS)

    Wende, H.; Li, Z.; Scherz, A.; Ceballos, G.; Baberschke, K.; Ankudinov, A.; Rehr, J. J.; Wilhelm, F.; Rogalev, A.; Schlagel, D. L.; Lograsso, T. A.

    2002-05-01

    We investigate the x-ray magnetic circular dichroism (XMCD) at the L3,2 edges using a single crystal of Tb as a prototype system for a one-element magnet in order to ascertain the multipolar nature of the features in the dichroic spectra. The high resolution of the experimental data allows for a clear identification of the dipolar (E1: 2p→5d) and quadrupolar (E2: 2p→4f) transitions. On the basis of ab initio calculations we developed a simple procedure to extract the quadrupolar part by subtracting the derivative of the spin-averaged absorption spectra from the experimental XMCD data. The deconvolution has to be carried out before applying sum rules to determine 4f and 5d moments.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  20. Earth2Class workshops for teachers: effective model linking researchers, educators, and students

    NASA Astrophysics Data System (ADS)

    Passow, M. J.; Assumpcao, C. M.; Baggio, F. D.

    2011-12-01

    The Earth2Class Workshops for Teachers at the Lamont-Doherty Earth Observatory of Columbia University (E2C) provide a successful model for disseminating scientific research to teachers and students. E2C takes a multifaceted approach to sharing cutting-edge discoveries, including monthly workshops that bring investigators together with classroom educator and their students, archived versions of the workshops and other educational resources accessible at www.earth2class.org, and active promotion of opportunities for teachers and students to engage directly with research scientists. The wide array of exploration conducted at LDEO have been showcased in more than 115 Saturday workshops since 1998, enabling more than 75 scientists to share their findings directly with over 250 middle and high school teachers and students. Each workshop features an introductory slideshow to provide background knowledge of the theme, the scientist(s)' presentation, and discussion of classroom applications. E2C website resources attract an average of more than 400,000 hits per month during the school year, extending the reach of the program to those unable to attend the workshops in Palisades, NY. E2C has come to be viewed at LDEO as a valid, effective venue to provide broader outreach, and several funded grants have included an E2C workshop in their proposals. Lamont scientists have easily been able to draw on E2C to connect with classroom teachers for a variety of research projects, including "River Summer," "A Day in the Life of the Hudson River," and "Data Puzzles." E2C teachers have assisted scientists during the annual Lamont Open House, which draws about 4,000 visitors. During the last two years, E2C has also co-organized the International Student and Teacher Exchange Program (ISTEP.) ISTEP has brought together high school students from New York City, Singapore, and the Netherlands to conduct field studies about water and soil chemistry, tree rings and forest diversity, and

  1. Low Earth orbital atomic oxygen and ultraviolet radiation effects on polymers

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.

    1991-01-01

    Because atomic oxygen and solar ultraviolet radiation present in the low earth orbital (LEO) environment can alter the chemistry of polymers resulting in degradation, their effects and mechanisms of degradation must be determined in order to determine the long term durability of polymeric surfaces to be exposed on missions such as Space Station Freedom. The effects of atomic oxygen on polymers which contain protective coatings must also be explored, since unique damage mechanisms can occur in areas where the protective coatings has failed. Mechanisms can be determined by utilizing results from previous LEO missions, by performing ground based LEO simulation tests and analysis, and by carrying out focussed space experiments. A survey is presented of the interactions and possible damage mechanisms for environmental atomic oxygen and UV radiation exposure of polymers commonly used in LEO.

  2. Proceedings of the NASA Workshop on Atomic Oxygen Effects. [low earth orbital environment

    NASA Technical Reports Server (NTRS)

    Brinza, David E. (Editor)

    1987-01-01

    A workshop was held to address the scientific issues concerning the effects of atomic oxygen on materials in the low Earth orbital (LEO) environment. The program included 18 invited speakers plus contributed posters covering topics such as LEO spaceflight experiments, interaction mechanisms, and atomic oxygen source development. Discussion sessions were also held to organize a test program to evaluate atomic oxygen exposure facilities. The key issues raised in the workshop were: (1) the need to develop a reliable predictive model of the effects of long-term exposure of materials to the LEO environment; (2) the ability of ground-based exposure facilities to provide useful data for development of durable materials; and (3) accurate determination of the composition of the LEO environment. These proceedings include the invited papers, the abstracts for the contributed posters, and an account of the test program discussion sessions.

  3. On the diamagnetic effect of the plasma sheet near 60 earth radii.

    NASA Technical Reports Server (NTRS)

    Meng, C.-I.; Mihalov, J. D.

    1972-01-01

    The two-dimensional (YZ plane) spatial distribution of magnetic field magnitudes in the geomagnetic tail at the lunar distance is given in both the solar magnetospheric and the neutral-sheet coordinate systems by using three years of data from the Ames magnetometer on Explorer 35. The effect of changes in geomagnetic activity is also presented. In the magnetotail near 60 earth radii, a broad region in which the magnetic field intensity is relatively weak in comparison with that in the other region of the tail is located adjacent to the solar magnetospheric equatorial plane and the calculated neutral sheet. This depression of the field due to the diamagnetic effect of the plasma sheet is more evident during times of minimum geomagnetic activity.-

  4. Low Earth orbital atomic oxygen and ultraviolet radiation effects on polymers

    SciTech Connect

    Dever, J.A.

    1991-02-01

    Because atomic oxygen and solar ultraviolet radiation present in the low earth orbital (LEO) environment can alter the chemistry of polymers resulting in degradation, their effects and mechanisms of degradation must be determined in order to determine the long term durability of polymeric surfaces to be exposed on missions such as Space Station Freedom. The effects of atomic oxygen on polymers which contain protective coatings must also be explored, since unique damage mechanisms can occur in areas where the protective coatings has failed. Mechanisms can be determined by utilizing results from previous LEO missions, by performing ground based LEO simulation tests and analysis, and by carrying out focussed space experiments. A survey is presented of the interactions and possible damage mechanisms for environmental atomic oxygen and UV radiation exposure of polymers commonly used in LEO.

  5. The Effect of Low Earth Orbit Atomic Oxygen Exposure on Phenylphosphine Oxide-Containing Polymers

    NASA Technical Reports Server (NTRS)

    Connell, John W.

    2000-01-01

    Thin films of phenylphosphine oxide-containing polymers were exposed to low Earth orbit aboard a space shuttle flight (STS-85) as part of flight experiment designated Evaluation of Space Environment and Effects on Materials (ESEM). This flight experiment was a cooperative effort between the NASA Langley Research Center (LaRC) and the National Space Development Agency of Japan (NASDA). The thin film samples described herein were part of an atomic oxygen exposure experiment (AOE) and were exposed to primarily atomic oxygen (1 X 1019 atoms/cm2). The thin film samples consisted of three phosphine oxide containing polymers (arylene ether, benzimidazole and imide). Based on post-flight analyses using atomic force microscopy, X-ray photoelectron spectroscopy, and weight loss data, it was found that atomic oxygen exposure of these materials efficiently produces a phosphate layer at the surface of the samples. This layer provides a barrier towards further attack by AO. Consequently, these materials do not exhibit linear erosion rates which is in contrast with most organic polymers. Qualitatively, the results obtained from these analyses compare favorably with those obtained from samples exposed to atomic oxygen and or oxygen plasma in ground based exposure experiments. The results of the low Earth orbit atomic oxygen exposure on these materials will be compared with those of ground based exposure to AO.

  6. North-South Asymmetries in Earth's Magnetic Field. Effects on High-Latitude Geospace

    NASA Astrophysics Data System (ADS)

    Laundal, K. M.; Cnossen, I.; Milan, S. E.; Haaland, S. E.; Coxon, J.; Pedatella, N. M.; Förster, M.; Reistad, J. P.

    2017-03-01

    The solar-wind magnetosphere interaction primarily occurs at altitudes where the dipole component of Earth's magnetic field is dominating. The disturbances that are created in this interaction propagate along magnetic field lines and interact with the ionosphere-thermosphere system. At ionospheric altitudes, the Earth's field deviates significantly from a dipole. North-South asymmetries in the magnetic field imply that the magnetosphere-ionosphere-thermosphere (M-I-T) coupling is different in the two hemispheres. In this paper we review the primary differences in the magnetic field at polar latitudes, and the consequences that these have for the M-I-T coupling. We focus on two interhemispheric differences which are thought to have the strongest effects: 1) A difference in the offset between magnetic and geographic poles in the Northern and Southern Hemispheres, and 2) differences in the magnetic field strength at magnetically conjugate regions. These asymmetries lead to differences in plasma convection, neutral winds, total electron content, ion outflow, ionospheric currents and auroral precipitation.

  7. Evidence of long term global decline in the Earth's thermospheric densities apparently related to anthropogenic effects

    NASA Astrophysics Data System (ADS)

    Keating, G. M.; Tolson, R. H.; Bradford, M. S.

    2000-05-01

    A study was performed of the long-term orbital decay of five Earth satellites with perigee altitudes averaging near 350km. To decouple long-term trend measurements from the effects of solar variability, measurements were evaluated during the years of solar minimum (1976, 1986 and 1996). Atmospheric densities derived from these essentially global measurements showed substantial evidence of a decline averaging 9.8 ± 2.5% in thermospheric density over 20 years pointing toward a long-term cooling of the upper atmosphere. Increases in greenhouse gases induced by human activity are hypothesized to warm the Earth's surface and lower atmosphere, but strongly cool the upper atmosphere. Assuming that the 10% increase in CO2 over these 20 years caused cooling resulting in the 10% decline in density, a doubling of CO2 could cause the thermospheric densities measured near 350km to decrease by a factor of 3. This decrease may shrink the altitude of a constant density surface by 40km before the end of the 21st century.

  8. Early Earth

    NASA Astrophysics Data System (ADS)

    Brown, M.

    2015-05-01

    Earth has continents, subduction and mobile lid plate tectonics, but details of the early evolution are poorly understood. Here I summarize the Hadean-Archean record, review evidence for a hotter Earth and consider geodynamic models for early Earth.

  9. On the possibility to detect multipolar order in URu2Si2 by the electric quadrupolar transition of resonant elastic x-ray scattering

    NASA Astrophysics Data System (ADS)

    Wang, Y. L.; Fabbris, G.; Meyers, D.; Sung, N. H.; Baumbach, R. E.; Bauer, E. D.; Ryan, P. J.; Kim, J.-W.; Liu, X.; Dean, M. P. M.; Kotliar, G.; Dai, X.

    2017-08-01

    Resonant elastic x-ray scattering is a powerful technique for measuring multipolar order parameters. In this paper, we theoretically and experimentally study the possibility of using this technique to detect the proposed multipolar order parameters in URu2Si2 at the U-L3 edge with the electric quadrupolar transition. Based on an atomic model, we calculate the azimuthal dependence of the quadrupolar transition at the U-L3 edge. The results illustrate the potential of this technique for distinguishing different multipolar order parameters. We then perform experiments on ultraclean single crystals of URu2Si2 at the U-L3 edge to search for the predicted signal, but do not detect any indications of multipolar moments within the experimental uncertainty. We theoretically estimate the orders of magnitude of the cross section and the expected count rate of the quadrupolar transition and compare them to the dipolar transitions at the U-M4 and U-L3 edges, clarifying the difficulty in detecting higher order multipolar order parameters in URu2Si2 in the current experimental setup.

  10. Investigating the effect of lateral viscosity variations in the Earth's mantle

    NASA Astrophysics Data System (ADS)

    O'Farrell, K. A.; Lithgow-Bertelloni, C. R.

    2015-12-01

    Seismic tomography can be used to investigate radial viscosity variations on instantaneous flow models by predicting the global geoid and comparing with the observed geoid. This method is one of many that has been used to constrain viscosity structure in the Earth's mantle in the last few decades. Using the 3D mantle convection model, Stag-YY (e.g., Hernlund and Tackley, 2008), we are further able to explore the effect of lateral variations in viscosity in addition to the radial variations. Examining over 50 tomographic models we found notable differences by comparing a synthetically produced geoid with the observed geoid. Comparing S- and P-wave tomographic models, the S-wave models provided a better fit to the observed geoid. Using this large suite of 50 tomographic models, we have been able to constrain the radial viscosity structure of the Earth. We found that two types of viscosity profiles yielded equally good fits. A viscosity profile with a low transition zone viscosity and a lower mantle viscosity equal to the upper mantle, or a profile with a large lower mantle viscosity and a transition zone viscosity similar to the upper mantle. Using the set of radial viscosity profiles that gave the best fit to the observed geoid, we can explore a range of lateral viscosity variations and see how they affect the different types of tomographic models. Improving on previous studies of lateral viscosity variations (e.g. Ghosh, Becker and Zhong, 2010), we systematically explore a large range of tomographic models and density-velocity conversion factors. We explore which type of tomographic model (S- or P- wave) is more strongly affected by lateral viscosity variations, as well as the effect on isotropic and anisotropic models. We constrain the strength of lateral viscosity variations necessary to produce a high correlation between observed and predicted geoid anomalies. We will discuss the wavelength of flow that is most affected by the lateral viscosity variations

  11. Solar Irradiance Changes And Photobiological Effects At Earth's Surface Following Astrophysical Ionizing Radiation Events

    NASA Astrophysics Data System (ADS)

    Thomas, Brian; Neale, Patrick

    2016-01-01

    Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth for decades. Although there is some direct biological damage on the surface from redistributed radiation several studies have indicated that the greatest long term threat is from ozone depletion and subsequent heightened solar ultraviolet (UV) radiation. It is known that organisms exposed to this irradiation experience harmful effects such as sunburn and even direct damage to DNA, proteins, or other cellular structures. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In the present work, we employed a radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light). Using biological weighting functions we have considered a wide range of effects, including: erythema and skin cancer in humans; inhibition of photosynthesis in the diatom Phaeodactylum sp. and dinoflagellate Prorocentrum micans inhibition of carbon fixation in Antarctic phytoplankton; inhibition of growth of oat (Avena sativa L. cv. Otana) seedlings; and cataracts. We found that past work overestimated UVB irradiance, but that relative estimates for increase in exposure to DNA damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in

  12. Effective dose measured with a life size human phantom in a low Earth orbit mission.

    PubMed

    Yasuda, Hiroshi

    2009-03-01

    The biggest concern about the health risk to astronauts is how large the stochastic effects (cancers and hereditary effects) of space radiation could be. The practical goal is to determine the "effective dose" precisely, which is difficult for each crew because of the complex transport processes of energetic secondary particles. The author and his colleagues thus attempted to measure an effective dose in space using a life-size human phantom torso in the STS-91 Shuttle-Mir mission, which flew at nearly the same orbit as that of the International Space Station (ISS). The effective dose for about 10-days flight was 4.1 mSv, which is about 90% of the dose equivalent (H) at the skin; the lowest H values were seen in deep, radiation-sensitive organs/tissues such as the bone marrow and colon. Succeeding measurements and model calculations show that the organ dose equivalents and effective dose in the low Earth orbit mission are highly consistent, despite the different dosimetry methodologies used to determine them.

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

    PubMed

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

    2011-08-01

    A fast and accurate fit program is presented for deconvolution of one-dimensional solid-state quadrupolar NMR spectra of powdered materials. Computational costs of the synthesis of theoretical spectra are reduced by the use of libraries containing simulated time/frequency domain data. These libraries are calculated once and with the use of second-party simulation software readily available in the NMR community, to ensure a maximum flexibility and accuracy with respect to experimental conditions. EASY-GOING deconvolution (EGdeconv) is equipped with evolutionary algorithms that provide robust many-parameter fitting and offers efficient parallellised computing. The program supports quantification of relative chemical site abundances and (dis)order in the solid-state by incorporation of (extended) Czjzek and order parameter models. To illustrate EGdeconv's current capabilities, we provide three case studies. Given the program's simple concept it allows a straightforward extension to include other NMR interactions. The program is available as is for 64-bit Linux operating systems. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Effects of low Earth orbit environment on the Long Duration Exposure Facility thermal control coatings

    NASA Technical Reports Server (NTRS)

    Sampair, Thomas R.; Berrios, William M.

    1992-01-01

    One of the benefits of the Long Duration Exposure Facility (LDEF) was the opportunity to study the before and after effects of low earth orbit space environment on the spacecraft thermal control coatings. Since the LDEF's thermal control was totally passive by design, the selection of the external surface absorptivity to emissivity ratio (alpha/epsilon) and the ability for the coating to retain the alpha/epsilon over time was an important consideration in the thermal design of the LDEF. The primary surface coating chosen for the LDEF structure was clear chromic anodized aluminum with an average design alpha/epsilon of 0.32/0.16. External surface absorptivity (alpha) and emissivity (epsilon) were measured on all intercostals, longerons, tray mounting flanges, thermal control panels, and a limited number of experiment surface coatings after the experiment trays were removed from the LDEF structure. All surface alpha/epsilon measurements were made using portable hand held infrared and solar spectrum reflectometers. The absorptivity measurements were taken with a Devices and Services SSR-ER version 5.0 solar spectra reflectometer which has a stated uncertainty of +/- 0.01, and all normal emissivity measurements were made using the Gier Dunkle DB-100 infrared reflectometer also with a stated uncertainty of +/- 0.01. Both instruments were calibrated in the laboratory by LaRC instrumentation personnel before being used in the field at KSC. A combined total of 733 measurements were taken on the anodized aluminum hardware which included the structure (intercostals, longerons, and center ring), earth and space end thermal control panels, and experiment tray mounting flanges. The facility thermal control coatings measured in this survey cover 33 percent of the total exposed LDEF surface area. To correlate low earth orbit environmental effects on the anodized coatings, measurements were taken in both exposed and unexposed surfaces and compared to quality assurance (QA

  15. Effects of low Earth orbit environment on the Long Duration Exposure Facility thermal control coatings

    NASA Technical Reports Server (NTRS)

    Sampair, Thomas R.; Berrios, William M.

    1992-01-01

    One of the benefits of the Long Duration Exposure Facility (LDEF) was the opportunity to study the before and after effects of low earth orbit space environment on the spacecraft thermal control coatings. Since the LDEF's thermal control was totally passive by design, the selection of the external surface absorptivity to emissivity ratio (alpha/epsilon) and the ability for the coating to retain the alpha/epsilon over time was an important consideration in the thermal design of the LDEF. The primary surface coating chosen for the LDEF structure was clear chromic anodized aluminum with an average design alpha/epsilon of 0.32/0.16. External surface absorptivity (alpha) and emissivity (epsilon) were measured on all intercostals, longerons, tray mounting flanges, thermal control panels, and a limited number of experiment surface coatings after the experiment trays were removed from the LDEF structure. All surface alpha/epsilon measurements were made using portable hand held infrared and solar spectrum reflectometers. The absorptivity measurements were taken with a Devices and Services SSR-ER version 5.0 solar spectra reflectometer which has a stated uncertainty of +/- 0.01, and all normal emissivity measurements were made using the Gier Dunkle DB-100 infrared reflectometer also with a stated uncertainty of +/- 0.01. Both instruments were calibrated in the laboratory by LaRC instrumentation personnel before being used in the field at KSC. A combined total of 733 measurements were taken on the anodized aluminum hardware which included the structure (intercostals, longerons, and center ring), earth and space end thermal control panels, and experiment tray mounting flanges. The facility thermal control coatings measured in this survey cover 33 percent of the total exposed LDEF surface area. To correlate low earth orbit environmental effects on the anodized coatings, measurements were taken in both exposed and unexposed surfaces and compared to quality assurance (QA

  16. Health Effects of Alkaline Diet and Water, Reduction of Digestive-tract Bacterial Load, and Earthing.

    PubMed

    Mousa, Haider Abdul-Lateef

    2016-04-01

    In the article, the author discusses the issue of chronic, low-grade acidosis that is thought to be brought about primarily by 2 factors: (1) advancing age, with a consequent decline in renal function; and (2) diet. An acid-forming diet can induce low-grade metabolic acidosis, which causes very small decreases in blood pH and plasma bicarbonate (HCO3-) that remain within the range considered to be normal. However, if the duration of the acidosis is prolonged or chronically present, even a low degree of acidosis can become significant. This article reviews supporting evidence in the literature that has shown that consumption of abundant alkaline-forming foods can result in improvement in bone mineral density (BMD) and muscle mass, protection from chronic illnesses, reduced tumor-cell invasion and metastasis, and effective excretion of toxins from the body. In addition, a large number of studies showing the benefits of alkaline water (mineral water) have revealed that people consuming water with a high level of total dissolved solids (TDS) (ie, with a high mineral content) have shown a lower incidence of coronary heart disease (CHD), cardiovascular disease (CVD), and cancer and lower total mortality rates. Consumption of alkaline water also may prevent osteoporosis and protect pancreatic beta cells with its antioxidant effects. In addition, this article discusses the literature that shows that reducing digestive-tract bacterial load can play an important role in increasing blood alkalinity toward the normal upper limit. That change occurs through good oral hygiene, flossing of teeth, perfect chewing of food, and bowel evacuation as soon as possible. Finally, the author reviews the literature that shows that earthing (ie, the direct contact of the human body with the earth) can supply a current of plentiful electrons. Earthing has been shown to reduce acute and chronic inflammation, blood glucose in patients with diabetes, red blood cell (RBC) aggregation, and blood

  17. Thermal inertia of near-Earth asteroids and magnitude of the Yarkovsky effect

    NASA Astrophysics Data System (ADS)

    Delbo, M.; Dell'Oro, A.; Harris, A. W.; Mottola, S.; Mueller, M.

    Thermal inertia of near-Earth asteroids and magnitude of the Yarkovsky effect M. Delbo* (1,2), A. Dell'Oro (2), A. W. Harris (3), S. Mottola (3), M. Mueller (3) (1) Observatoire de la Côte d'Azur B.P. 4229, 06034 Nice Cedex 4, France. (2) INAF-Osservatorio Astr. di Torino, via Osservatorio 20, 10025 Pino Torinese (TO), Italy. (3) DLR Institute of Planetary Research, Rutherfordstrasse 2, 12489 Berlin, Germany. Thermal inertia is the physical parameter that controls the temperature distribution over the surface of an asteroid. It affects the strength of the Yarkovsky effect, which causes orbital drift of km-sized asteroids and is invoked to explain the delivery of near-Earth asteroids (NEAs) from the main belt. Measurements of thermal inertia provide information on the presence or absence of loose surface material, such as thermally insulating regolith or dust. Such information is not only important for scientific studies of asteroid surface properties, but it is also vital for the design of lander missions and in the development of technology for the deflection of hazardous asteroids. At present, very little is known about the thermal inertia of asteroids in the km size range. Here we report on a method that has allowed us to derive a mean value for the thermal inertia of near-Earth asteroids on the basis of multi-wavelength thermal-infrared observations. We obtain a mean value of 200 ± 50 J m-2 s-0.5 K -1 corresponding to a surface thermal conductivity of 0.03 ± 0.01 W m-1 K-1 . We also identify a trend of increasing thermal inertia with decreasing asteroid size. As a consequence, the dependence of the Yarkovsky-induced semimajor axis drift rate on object diameter, D, departs from the 1/D dependence commonly assumed in models of the dynamical evolution of asteroids. *The work of Marco Delbo has been partially supported by the European Space Agency (ESA).

  18. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1989-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  19. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1990-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  20. Sheath effects observed on a 10 meter high voltage panel in simulated low earth orbit plasma

    NASA Technical Reports Server (NTRS)

    Mccox, J. E.; Konradi, A.

    1979-01-01

    A large (1m x 10m) flat surface of conductive material was biased to high voltage (+ or - 3000 V) to simulate the behavior of a large solar array in low earth orbit. The model array was operated in a plasma environment of 1,000 to 1,000,000/cu cm, with sufficient free space around it for the resulting plasma sheaths to develop unimpeded for 5-10 meters into the surrounding plasma. Measurements of the resulting sheath thickness were obtained. The observed thickness varied approximately as V to the 3/4 power and N to the 1/2 power. This effect appears to limit total current leakage from the test array until sheath dimensions exceed about 1 meter. Total leakage current was also measured with the array.

  1. Relationship between microstructure and efficiency of lithium silicate scintillating glasses: The effect of alkaline earths

    SciTech Connect

    Bliss, M.; Craig, R.A.; Sunberg, D.S.; Weber, M.J.

    1996-12-31

    Lithium silicate glasses containing Ce{sup 3+} are known to be scintillators. Glasses in this family in which the Li is enriched ({sup 6}Li) are used as neutron detectors. The addition of Mg to this glass is known to increase the scintillation efficiency. We have found that substituting other alkaline earths results in a monotonic decrease of the scintillation efficiency with increasing atomic number. The total variation in scintillation efficiency from Mg to Ba is nearly a factor of 3. Prior experiments with this glass family show small differences in Raman and fluorescence spectra; evidence from thermoluminescence experiments indicates that the scintillation efficiency is most strongly correlated with structural effects in the neighborhood of the Ce{sup 3+} activator ion. The results of low-temperature studies of fluorescence and thermoluminescence of these glasses will be reported.

  2. Ammonia photolysis and the greenhouse effect in the primordial atmosphere of the earth

    NASA Technical Reports Server (NTRS)

    Kuhn, W. R.; Atreya, S. K.

    1979-01-01

    Photochemical calculations indicate that in the prebiotic atmosphere of earth ammonia would have been irreversibly converted to N2 in less than 40 years if the ammonia surface mixing ratio were no more than 0.0001. However, if a continuous outgassing of ammonia were maintained, radiative-equilibrium calculations indicate that a surface mixing ratio of ammonia of 0.0001 or greater would provide a sufficient greenhouse effect to keep the surface temperature above freezing. With a 0.0001 mixing ratio of ammonia, 60% to 70% of the present-day solar luminosity would be adequate to maintain surface temperatures above freezing. A lower limit to the time constant for accumulation of an amount of nitrogen equivalent to the present day value is 10 my if the outgassing were such as to provide a continuous surface mixing ratio of ammonia of at least 0.00001.

  3. Sheath effects observed on a 10 meter high voltage panel in simulated low earth orbit plasma

    NASA Technical Reports Server (NTRS)

    Mccox, J. E.; Konradi, A.

    1979-01-01

    A large (1m x 10m) flat surface of conductive material was biased to high voltage (+ or - 3000 V) to simulate the behavior of a large solar array in low earth orbit. The model array was operated in a plasma environment of 1,000 to 1,000,000/cu cm, with sufficient free space around it for the resulting plasma sheaths to develop unimpeded for 5-10 meters into the surrounding plasma. Measurements of the resulting sheath thickness were obtained. The observed thickness varied approximately as V to the 3/4 power and N to the 1/2 power. This effect appears to limit total current leakage from the test array until sheath dimensions exceed about 1 meter. Total leakage current was also measured with the array.

  4. Oblate-Earth Effects on the Calculation of Ec During Spacecraft Reentry

    NASA Technical Reports Server (NTRS)

    Bacon, John B.; Matney, Mark

    2017-01-01

    The bulge in the Earth at its equator has been shown to lead to a clustering of natural decays biased to occur towards the equator and away from the orbit's extreme latitudes. Such clustering must be considered when predicting the Expectation of Casualty (Ec) during a natural decay, because of the corresponding clustering of the human population in the lower latitudes. This study expands upon prior work, and formalizes in a single empirical equation the correction that must be made to the calculation of the average exposed population density as a result of this effect. The equation is represented as a function of ballistic number and inclination of the entering spacecraft over the credible range of ballistic numbers.

  5. Precise analytical description of the Earth matter effect on oscillations of low energy neutrinos

    SciTech Connect

    Ioannisian, A.N.; Kazarian, N.A.; Smirnov, A.Yu.; Wyler, D.

    2005-02-01

    We present a formalism for the matter effects in the Earth on low energy neutrino fluxes which is both accurate and has all the advantages of a full analytic treatment. The oscillation probabilities are calculated up to the second order term in {epsilon}(x){identical_to}2V(x)E/{delta}m{sup 2}, where V(x) is the neutrino potential at position x. We show the absence of large undamped phases which makes the expansion in {epsilon} well behaved. An improved expansion is presented in terms of the variation of V(x) around a suitable mean value which allows one to treat energies up to those relevant for supernova neutrinos. We discuss also the case of three-neutrino mixing.

  6. Energetic interplanetary nucleon flux anisotropies - The effect of earth's bow shock and magnetosheath on sunward flow

    NASA Technical Reports Server (NTRS)

    Christon, S. P.

    1982-01-01

    Attention is given to the combined, average effects of the bow shock and magnetosheath on the diffusive flow of interplanetary nuclei. The observations presented show that differences between 'connected' and 'unconnected' data subsets are apparent from the beginning of the analysis. Through an investigation of the mean unconnected diffusive anisotropy (those fluxes least affected by the earth's bow shock and magnetosheath) it is confirmed that the cross-field transport of MeV energy nuclei in interplanetary space is statistically significant and in the direction expected from the large-scale particle flux gradients. The direction of particle flow relative to the IMF is then used to show that nucleon flow characteristics on connected IMF differ from those on unconnected IMF. A scenario for producing this difference is then presented. It is concluded that the inclusion of the bow shock connected information biases measurements of the flux anisotropies of MeV energy H.

  7. Cost-effective technology advancement directions for electric propulsion transportation systems in earth-orbital missions

    NASA Technical Reports Server (NTRS)

    Regetz, J. D., Jr.; Terwilliger, C. H., Jr.

    1979-01-01

    This paper presents the results of a study to determine the directions that electric propulsion technology should take to meet the primary propulsion requirements for earth-orbital missions of the next three decades in the most cost-effective manner. Discussed are the mission set requirements, state-of-the-art electric propulsion technology and the baseline system characterized by it, adequacy of the baseline system to meet the mission set requirements, cost-optimum electric propulsion system characteristics for the mission set, and sensitivities of mission costs and design points to system-level electric propulsion parameters. It is found that the efficiency-specific impulse characteristic generally has a more significant impact on overall costs than specific masses or costs of propulsion and power systems.

  8. Ammonia photolysis and the greenhouse effect in the primordial atmosphere of the earth

    NASA Technical Reports Server (NTRS)

    Kuhn, W. R.; Atreya, S. K.

    1979-01-01

    Photochemical calculations indicate that in the prebiotic atmosphere of earth ammonia would have been irreversibly converted to N2 in less than 40 years if the ammonia surface mixing ratio were no more than 0.0001. However, if a continuous outgassing of ammonia were maintained, radiative-equilibrium calculations indicate that a surface mixing ratio of ammonia of 0.0001 or greater would provide a sufficient greenhouse effect to keep the surface temperature above freezing. With a 0.0001 mixing ratio of ammonia, 60% to 70% of the present-day solar luminosity would be adequate to maintain surface temperatures above freezing. A lower limit to the time constant for accumulation of an amount of nitrogen equivalent to the present day value is 10 my if the outgassing were such as to provide a continuous surface mixing ratio of ammonia of at least 0.00001.

  9. Health effects and toxicity mechanisms of rare earth elements-Knowledge gaps and research prospects.

    PubMed

    Pagano, Giovanni; Guida, Marco; Tommasi, Franca; Oral, Rahime

    2015-05-01

    In the recent decades, rare earth elements (REE) have undergone a steady spread in several industrial and medical applications, and in agriculture. Relatively scarce information has been acquired to date on REE-associated biological effects, from studies of bioaccumulation and of bioassays on animal, plant and models; a few case reports have focused on human health effects following occupational REE exposures, in the present lack of epidemiological studies of occupationally exposed groups. The literature is mostly confined to reports on few REE, namely cerium and lanthanum, whereas substantial information gaps persist on the health effects of other REE. An established action mechanism in REE-associated health effects relates to modulating oxidative stress, analogous to the recognized redox mechanisms observed for other transition elements. Adverse outcomes of REE exposures include a number of endpoints, such as growth inhibition, cytogenetic effects, and organ-specific toxicity. An apparent controversy regarding REE-associated health effects relates to opposed data pointing to either favorable or adverse effects of REE exposures. Several studies have demonstrated that REE, like a number of other xenobiotics, follow hormetic concentration-related trends, implying stimulatory or protective effects at low levels, then adverse effects at higher concentrations. Another major role for REE-associated effects should be focused on pH-dependent REE speciation and hence toxicity. Few reports have demonstrated that environmental acidification enhances REE toxicity; these data may assume particular relevance in REE-polluted acidic soils and in REE mining areas characterized by concomitant REE and acid pollution. The likely environmental threats arising from REE exposures deserve a new line of research efforts. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Effects of CubeSat Deployments in Low-Earth Orbit

    NASA Technical Reports Server (NTRS)

    Matney, M. J.; Vavrin, A. B.; Manis, A. P.

    2017-01-01

    Long-term models, such as NASA's LEGEND (LEO (Low-Earth Orbit)-to-GEO (Geosynchrous Earth Orbit) Environment Debris) model, are used to make predictions about how space activities will affect the long-term evolution of the debris environment. Part of this process is to predict how spacecraft and rocket bodies will be launched and left in the environment in the future. This has usually been accomplished by repeating past launch history to simulate future launches. It was partially upon the basis of the results of such models that both national and international orbital debris mitigation guidelines - especially the "25-year rule" for post-mission disposal - were determined. The proliferation of Cubesat launches in recent years, however, has raised concerns that we are seeing a fundamental shift in how humans launch satellites into space that may alter the assumptions upon which our current mitigation guidelines are based. The large number of Cubesats, and their short lifetime and general inability to perform collision avoidance, potentially makes them an important new source of debris. The NASA Orbital Debris Program Office (ODPO) has conducted a series of LEGEND computations to investigate the long-term effects of adding Cubesats to the environment. Several possible future scenarios were simulated to investigate the effects of the size of future Cubesat launches and the efficiency of post-mission disposal on the proliferation of catastrophic collisions over the next 200 years. These results are compared to a baseline "business-as-usual" scenario where launches are assumed to continue as in the past without major Cubesat deployments. Using these results, we make observations about the continued use of the 25-year rule and the importance of the universal application of post-mission disposal. We also discuss how the proliferation of Cubesats may affect satellite traffic at lower altitudes.

  11. The Effect of Rare Earth Dopants in Crystal Structure of Bi-2212 Superconductor

    NASA Astrophysics Data System (ADS)

    Suharta, W. G.; Widagda, IGA.; Putra, K.; Suyanto, H.

    2017-03-01

    Bi2Sr2CaCu2O8+∂ samples have been successfully synthesized by doping rare earth (RE) variations using wet-mixing method. Samples calcined at 600°C for 3 hours and sintered at 850°C for 10 hours. The purpose of research is to determine the effect of the RE dopant on the microscopic structure of BSCRECO superconductors. Therefore, the research was conducted characterization by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Measurements with XRD could be carried out and crystal system of Bi2Sr2CaCu2O8+∂ with rare earth (RE) dopants could be determined clearly. Generally, crystallization has occurred very well demonstrated by the diffraction peaks are sharp, which is dominated by the emergence of Bi-2212 phase. Search match results of XRD spectrum showed Bi2Sr2CuOx (2201) and Ca2CuO3 (21) as an impurity phase with small intensity. Also, that is showing volume fraction from 85 to 92% and orthorombic value for all samples from 5 to 7%. The effect of RE dopants resulted a shift angle 2θ and changes in the volume of the unit cells of each sample. The value of the unit cell volume of the largest to smallest is BS(CN)CO, BS(CNG)CO, BS(CNEG)CO, BS(CNE)CO, BS(CG)CO, BS(CEG)CO and BS(CE)CO. Measurement with FTIR showed the bending vibration absorption by CO3 2- in the wavelength range between 1500 and 1520 cm-1, vibration of M-O between 420 and 650 cm-1, the complex formation of BSCCO in the wavelength range between 1690 and 1700 cm-1. Measurement with SEM showed rod shape with particle size in hundreds nanometer.

  12. Effects of sediment transport and deposition on crustal loading, Earth's gravitational field, and sea level

    NASA Astrophysics Data System (ADS)

    Ferrier, K.; Mitrovica, J. X.; Perron, T.; Milne, G. A.; Wickert, A. D.

    2012-12-01

    Spatial patterns in static sea level are controlled by the interplay between the history of ice mass variations and the associated deformational, gravitational and rotational perturbations in the Earth's state. Over the last decade, there has been a renewed effort to extend classic treatments of ice-age sea-level change (Farrell and Clark, 1976) to incorporate effects such as shoreline migration due to the local onlap or offlap of seawater and changes in the extent of grounded, marine-based ice, as well as feedbacks between sea level and the orientation of Earth's rotation axis. To date, the impact of sediment transport - whether in the context of glacial processes, or other processes such as fluvial deposition - has not been incorporated into a gravitationally self-consistent sea-level theory. Here we briefly summarize the main elements of a new sea-level theory that includes sediment transport, and we apply this new theory to investigate crustal deformation and sea-level changes driven by sediment deposition on the Mississippi fan in the Gulf of Mexico. The calculations incorporate sediment transport from the start of the last glacial cycle through to the present and are constrained to conserve sediment and ocean mass. We compare relative sea level histories predicted with and without sediment transport at sites in and around the Gulf of Mexico, and we quantify the relative impacts of gravitational and deformational effects of sediment deposition. We also explore the extent to which sea-level changes associated with sediment transport impact the interpretation of paleo-sea-level records. Our new sea-level formulation provides an important component of a comprehensive coupling between sediment transfer and sea level on local, regional and global spatial scales, and on time scales extending from decades to tens of thousands of years. References: Farrell, W.E., and Clark, J.A., 1976. On postglacial sea level: Geophysical Journal of the Royal Astronomical Society, v

  13. Effect of gravity on terminal particle settling velocity on Moon, Mars and Earth

    NASA Astrophysics Data System (ADS)

    Kuhn, Nikolaus J.

    2013-04-01

    Gravity has a non-linear effect on the settling velocity of sediment particles in liquids and gases due to the interdependence of settling velocity, drag and friction. However, StokeśLaw, the common way of estimating the terminal velocity of a particle moving in a gas of liquid assumes a linear relationship between terminal velocity and gravity. For terrestrial applications, this "error" is not relevant, but it may strongly influence the terminal velocity achieved by settling particles on Mars. False estimates of these settling velocities will, in turn, affect the interpretation of particle sizes observed in sedimentary rocks on Mars. Wrong interpretations may occur, for example, when the texture of sedimentary rocks is linked to the amount and hydraulics of runoff and thus ultimately the environmental conditions on Mars at the time of their formation. A good understanding of particle behaviour in liquids on Mars is therefore essential. In principle, the effect of lower gravity on settling velocity can also be achieved by reducing the difference in density between particle and gas or liquid. However, the use of such analogues simulating the lower gravity on Mars on Earth is creates other problems because the properties (i.e. viscosity) and interaction of the liquids and sediment (i.e. flow around the boundary layer between liquid and particle) differ from those of water and mineral particles. An alternative for measuring the actual settling velocities of particles under Martian gravity, on Earth, is offered by placing a settling tube on a reduced gravity flight and conduct settling tests within the 20 to 25 seconds of Martian gravity that can be simulated during such a flight. In this presentation we report the results of such a test conducted during a reduced gravity flight in November 2012. The results explore the strength of the non-linearity in the gravity-settling velocity relationship for terrestrial, lunar and Martian gravity.

  14. Solar irradiance changes and photobiological effects at earth's surface following astrophysical ionizing radiation events.

    PubMed

    Thomas, Brian C; Neale, Patrick J; Snyder, Brock R

    2015-03-01

    Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the Tropospheric Ultraviolet and Visible (TUV) radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light) for clear-sky conditions and fixed aerosol parameter values. We also considered a wide range of biological effects on organisms ranging from humans to phytoplankton. We found that past work overestimated UVB irradiance but that relative estimates for increase in exposure to DNA-damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in very limited geographical areas; instead we found a net increase for most of the modeled time-space region. This result has implications for proposed climate changes associated with ionizing radiation events.

  15. Changes in the Earth's Spin Rotation due to the Atmospheric Effects and Reduction in Glaciers

    NASA Astrophysics Data System (ADS)

    Na, Sung-Ho; Cho, Jungho; Kim, Tu-Hwan; Seo, Kiweon; Youm, Kookhyoun; Yoo, Sung-Moon; Choi, Byungkyu; Yoon, Hasu

    2016-12-01

    The atmosphere strongly affects the Earth's spin rotation in wide range of timescale from daily to annual. Its dominant role in the seasonal perturbations of both the pole position and spinning rate of the Earth is once again confirmed by a comparison of two recent data sets; i) the Earth orientation parameter and ii) the global atmospheric state. The atmospheric semi-diurnal tide has been known to be a source of the Earth's spin acceleration, and its magnitude is re-estimated by using an enhanced formulation and an up-dated empirical atmospheric S2 tide model. During the last twenty years, an unusual eastward drift of the Earth's pole has been observed. The change in the Earth's inertia tensor due to glacier mass redistribution is directly assessed, and the recent eastward movement of the pole is ascribed to this change. Furthermore, the associated changes in the length of day and UT1 are estimated.

  16. The Effect of Teaching Strategies Using Models on Preservice Elementary Teachers' Conceptions about Earth-Sun-Moon Relationships.

    ERIC Educational Resources Information Center

    Callison, Priscilla L.; Wright, Emmett L.

    This study investigated the effect of three specific hands-on teaching strategies on the attainment and alteration of preservice elementary teachers' conceptions about earth-sun-moon relationships. The subjects (n=76) were enrolled in an elementary school science methods course. The descriptive nature of this study explored: (1) the effect of two…

  17. Semi analytical model for the effective grain size profile in the mantle of the Earth: partitioning between diffusion and dislocation creep through the Earth's history

    NASA Astrophysics Data System (ADS)

    Rozel, A. B.; Golabek, G.; Thielmann, M.; Tackley, P.

    2015-12-01

    We present a semi analytical model of mantle convection able to predict the grain size profile of the present day Earth. Grain size evolution has been studied with increasing interest over the last decades but its behavior in both mantle and lithosphere remains largely misunderstood due to its non-linearity. Several recent studies suggest that it might play a fundamental role in localization of deformation in the lithosphere but we focus here on the mantle in which we also observe important processes.We propose a 1D compressible thermal convection model based on the equality of advective heat flux and the integral of viscous dissipation in the whole domain. Imposing mass conservation, our model is able to predict all rheological parameters able to produce both present day average surface velocity and lower mantle viscosity. Composite rheologies involving dislocation creep and grain size dependent diffusion creep are considered. The effect of phase transitions on the grain size is also explicitely taken into account. We present the family of solutions for the activation volume and the viscosity jump at the 660 discontinuity according to any initial choice of activation energy. The scaling laws for rheological parameters obtained are compared to self-consistent evolutionary simulations of mantle convection in 2D spherical annulus geometry considering composite rheologies. The transition between diffusion and dislocation creep due to the cooling of the Earth is illustrated in a set of numerical simulations starting from the physical conditions of the Archean.

  18. The Effects of Solar Variability on Earth's Climate: A Workshop Report

    NASA Technical Reports Server (NTRS)

    2012-01-01

    varbility and Earth s climate is multifaceted and that some components are understood better than others. According to two presenters on paleoclimate, there is a need to study the idiosyncrasies of each key proxy record. Yet they also emphasized that there may be an emerging pattern of paleoclimate change coincident with periods of solar activity and inactivity, but only on long timescales of multiple decades to millennia. Several speakers discussed the effects of particle events and cosmic-ray variability. These are all areas of exciting fundamental research; however, they have not yet led to conclusive evidence for significant related climate effects. The key problem of attribution of climate variability on the timescales of the Little Ice Age and the Maunder Minimum were directly addressed in several presentations. Several workshop participants remarked that the combination of solar, paleoclimatic, and climate modeling research has the potential to dramatically improve the credibility of these attribution studies.

  19. The Effects of Solar Variability on Earth's Climate: A Workshop Report

    NASA Technical Reports Server (NTRS)

    2012-01-01

    varbility and Earth s climate is multifaceted and that some components are understood better than others. According to two presenters on paleoclimate, there is a need to study the idiosyncrasies of each key proxy record. Yet they also emphasized that there may be an emerging pattern of paleoclimate change coincident with periods of solar activity and inactivity, but only on long timescales of multiple decades to millennia. Several speakers discussed the effects of particle events and cosmic-ray variability. These are all areas of exciting fundamental research; however, they have not yet led to conclusive evidence for significant related climate effects. The key problem of attribution of climate variability on the timescales of the Little Ice Age and the Maunder Minimum were directly addressed in several presentations. Several workshop participants remarked that the combination of solar, paleoclimatic, and climate modeling research has the potential to dramatically improve the credibility of these attribution studies.

  20. Ground shock from multiple earth penetrator bursts: Effects for hexagonal weapon arrays

    SciTech Connect

    Kmetyk, L.N.; Yarrington, P.

    1990-08-01

    Calculations have been performed with the HULL hydrocode to study ground shock effects for multiple earth penetrator weapon (EPW) bursts in hexagonal-close-packed (HCP) arrays. Several different calculational approaches were used to treat this problem. The first simulations involved two-dimensional (2D) calculations, where the hexagonal cross-section of a unit-cell in an effectively-infinite HCP array was approximated by an inscribed cylinder. Those calculations showed substantial ground shock enhancement below the center of the array. To refine the analysis, 3D unit-cell calculations were done where the actual hexagonal cross-section of the HCP array was modelled. Results of those calculations also suggested that the multiburst array would enhance ground shock effects over those for a single burst of comparable yield. Finally, 3D calculations were run in which an HCP array of seven bursts was modelled explicitly. In addition, the effects of non-simultaneity were investigated. Results of the seven-burst HCP array calculations were consistent with the unit-cell results and, in addition, provided information on the 3D lethal contour produced by such an array.

  1. Carbon sequestration potential and climatic effects of reforestation in an Earth system model

    NASA Astrophysics Data System (ADS)

    Sonntag, Sebastian; Pongratz, Julia; Reick, Christian; Schmidt, Hauke

    2015-04-01

    Studies on the global climatic effects of afforestation have mainly focused on the carbon sequestration potential of plausible scenarios while neglecting biogeophysical effects or were based on highly idealised afforestation scenarios. Here we assess the reduction potential for the atmospheric CO2 concentration and possible consequences for the global climate of following a strong reforestation scenario during this century taking into account both biogeochemical and biogeophysical effects. We perform simulations using the Max Planck Institute for Meteorology Earth System Model (MPI-ESM), forced by anthropogenic emissions according to the Representative Concentration Pathway (RCP) 8.5, but using land use transitions according to RCP 4.5. Thereby we are able to isolate the effects of land use changes in this scenario in which agricultural intensification leads to abandonment of agricultural areas and a regrowth of forest of about 8 million km2 in our model. We find that this reforestation reduces the atmospheric CO2 concentration by about 85 ppm by the end of the century as compared to RCP 8.5. This value is higher than previous estimates for plausible reforestation scenarios, mostly because the CO2 fertilisation effect on the terrestrial vegetation has not been accounted for in previous studies. Due to the lower CO2 concentration the global mean temperature increase is reduced by about 0.27 K. Regionally the simulated effect may exceed 2 K, but the largest annual mean cooling signal occurs in only sparsely populated regions. Concerning temperature extremes, however, the effect can also be large in densely populated areas, mostly caused by local biogeophysical effects of the vegetation changes. Thus, we conclude that the mitigation potential of reforestation is higher than previously thought, the need for adaptation in many regions of the world is still strong, but temperature extremes may be reduced.

  2. Preliminary evaluation of effects of best management practices in the Black Earth Creek, Wisconsin, priority watershed

    USGS Publications Warehouse

    Walker, J.F.; Graczyk, D.J.; Olem, H.

    1993-01-01

    Nonpoint-source contamination accounts for a substantial part of the water quality problems in many watersheds. The Wisconsin Nonpoint Source Water Pollution Abatement Program provides matching money for voluntary implementation of various best management practices (BMPs). The effectiveness of BMPs on a drainage-basin scale has not been adequately assessed in Wisconsin by use of data collected before and after BMP implementation. The U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources, monitored water quality in the Black Earth Creek watershed in southern Wisconsin from October 1984 through September 1986 (pre-BMP conditions). BMP implementation began during the summer of 1989 and is planned to continue through 1993. Data collection resumed in fall 1989 and is intended to provide information during the transitional period of BMP implementation (1990-93) and 2 years of post-BMP conditions (1994-95). Preliminary results presented for two subbasins in toe Black Earth Creek watershed (Brewery and Garfoot Creeks) are based on data collected during pre-BMP conditions and the first 3 years of the transitional period. The analysis includes the use of regressions to control for natural variability in the data and, hence, enhance the ability to detect changes. Data collected to date (1992) indicate statistically significant differences in storm mass transport of suspended sediment and ammonia nitrogen at Brewery Creek. The central tendency of the regression residuals has decreased with the implementation of BMPs; hence, the improvement in water quality in the Brewery Creek watershed is likely a result of BMP implementation. Differences in storm mass transport at Garfoot Creek were not detected, primarily because of an insufficient number of storms in the transitional period. As practice implementation continues, the additional data will be used to determine the level of management which results in significant improvements in water

  3. Quadrupolar interaction of ^57Fe in compounds RENi_2B_2C: Experimental and Theoretical Studies

    NASA Astrophysics Data System (ADS)

    Zeng, Zhi; Guenzburger, Diana; Sanchez, D. R. S.; Bud'Ko, S. L.; Fontes, Magda B.; Baggia-Saitovitch, E. M.; Ellis, D. E.

    1996-03-01

    ^57Fe Mössbauer spectra were taken with the RE(Ni_0.99^57Fe_0.01)_2B_2C (RE=Tb, Dy, Ho, Er) samples in a variable temperature helium crysostat to study the interplay between superconductivity and magnetism in the RENi_2B_2C (RE=Dy, Ho, Er, Tm) compounds. The rare earth dependent quadrupole splitting (QS) from ^57Fe Mössbauer spectra decreases with the lanthanide contraction^footnotetext^The lanthanide contraction causes an increase in the ratio c/a along the RE series. from QS=0.27mm/s for TbNi_2B_2C to QS=0.14mm/s for ErNi_2B_2C. Self-consistent frist-principles electronic structure calculation[1] were performed for clusters with 71 atoms (Fe-12RE-14Ni-32B-12C), which were embedded in the charge denisity of several shells of neighbours in the crystal, representing the doped compounds RE(Ni_0.93Fe_0.07)_2B_2C (RE=Gd, Tb, Dy, Ho, and Er). The quadrupole splitting was obtained with the nuclear quadrupole moment Q=0.16b of ^57Fe[2]. The calculated results are in good agreement with experiment. The theoretical results give negative signs for all the QS values; which have not been determined by experiment, except for the compounds with Tb and Ho, for which they are negative. REFERENCES D.E. Ellis, Int. J. Quant. Chem. Suppl. 2, 35(1968); D.E. Ellis and G.S. Painter, Phys. Rev. B, 2, 2887(1970). Ohilipp Dufek, Peter Blaha and K. Schwarz, Phys. Rev. Lett. 75, 3545(1995).

  4. Tissue deposition and toxicological effects of commercially significant rare earth oxide nanomaterials: Material and physical properties.

    PubMed

    Das, Soumen; Reed McDonagh, Philip; Selvan Sakthivel, Tamil; Barkam, Swetha; Killion, Kelsey; Ortiz, Julian; Saraf, Shashank; Kumar, Amit; Gupta, Ankur; Zweit, Jamal; Seal, Sudipta

    2017-03-01

    Rare earth oxide (REO) materials are found naturally in earth's crust and at the nanoscale these REO nanoparticles exhibit unique thermal, electrical, and physicochemical properties. REO nanoparticles are widely used in different industrial sectors for ceramics, glass polishing, metallurgy, lasers, and magnets. Recently, some of these REO nanoparticles have been identified for their potential application in medicine, including therapy, imaging, and diagnostics. Concurrent research into the REO nanomaterials' toxicities has also raised concern for their environmental impacts. The correlation of REO nanoparticles mediated toxicity with their physiochemical properties can help to design nanoparticles with minimal effect on the environment and living organisms. In vitro assay revealed toxicity toward Human squamous epithelial cell line (CCL30) and Human umbilical vascular endothelial cells (HUVEC) at a concentration of 100 µM and higher. In vivo results showed, with the exception of CeO2 and Gd2 O3 , most of the naoparticles did not clear or had minimum clearance (10-20%) from the system. Elevated levels of alanine transferase were seen for animals given each different nanoparticle, however the increases were not significant for CeO2 and Dy2 O3 . Nephrotoxicity was only seen in case of Dy2 O3 and Gd2 O3 . Lastly, histological examination revealed presence of swollen hepatocytes which further confirms toxicity of the commercial REO nanomaterials. The in vivo toxicity is mainly due to excessive tissue deposition (70-90%) due to the commercial REO nanoparticles' poor physical properties (shape, stability, and extent of agglomeration). Therefore, optimization of nanoparticles physical properties is very important. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 904-917, 2017. © 2016 Wiley Periodicals, Inc.

  5. External and internal magnetic-field effects on ferroelectricity in orthorhombic rare-earth manganites

    NASA Astrophysics Data System (ADS)

    Kuwahara, H.; Noda, K.; Akaki, M.

    2006-03-01

    We report the dielectric and magnetic properties of the perovskite (Eu,Y)MnO3 crystal without the presence of the 4f magnetic moments of the rare earth ions. The subject compound, (Eu,Y)MnO3, was controlled the average ionic radius of the A site so that it was the same as that of TbMnO3 in which the intriguing magnetoelectric effect has been recently discovered. The (Eu,Y)MnO3 crystal was found to have two distinct ferroelectric phases with polarization along the a (Pa, T<=23K) and c (Pc, 23K<=T<=25K) axes in the orthorhombic Pbnm setting in a zero magnetic field. In addition, we have demonstrated a magnetic-field-induced switching between these ferroelectric phases: Pa changed to Pc by the application of magnetic fields parallel to the a axis (Ha). In analogy to the case of Pc in TbMnO3, this result is possibly interpreted as follows. In the case of (Eu,Y)MnO3, Mn 3d spins rotate in the ab plane and Pa would emerge in a zero field. In the Ha, the field will force the spins to rotate in the bc plane, in which Pc would be stabilized. Magnetization measurements supported this interpretation: We confirmed the change of the spin rotation axis of the helix from the c axis to the a axis induced by application of the Ha because there is no 4f moments acting as an internal magnetic field and interacting with the 3d spins. Results obtained with other rare-earth manganites such as (Gd,Tb)MnO3 and (Eu,Ho)MnO3 will be presented.

  6. Effect of hydrocarbon adsorption on the wettability of rare earth oxide ceramics

    SciTech Connect

    Preston, Daniel J.; Miljkovic, Nenad; Sack, Jean; Queeney, John; Wang, Evelyn N.; Enright, Ryan

    2014-07-07

    Vapor condensation is routinely used as an effective means of transferring heat, with dropwise condensation exhibiting a 5 − 7x heat transfer improvement compared to filmwise condensation. However, state-of-the-art techniques to promote dropwise condensation rely on functional hydrophobic coatings, which are often not robust and therefore undesirable for industrial implementation. Natural surface contamination due to hydrocarbon adsorption, particularly on noble metals, has been explored as an alternative approach to realize stable dropwise condensing surfaces. While noble metals are prohibitively expensive, the recent discovery of robust rare earth oxide (REO) hydrophobicity has generated interest for dropwise condensation applications due to material costs approaching 1% of gold; however, the underlying mechanism of REO hydrophobicity remains under debate. In this work, we show through careful experiments and modeling that REO hydrophobicity occurs due to the same hydrocarbon adsorption mechanism seen previously on noble metals. To investigate adsorption dynamics, we studied holmia and ceria REOs, along with control samples of gold and silica, via X-Ray photoelectron spectroscopy (XPS) and dynamic time-resolved contact angle measurements. The contact angle and surface carbon percent started at ≈0 on in-situ argon-plasma-cleaned samples and increased asymptotically over time after exposure to laboratory air, with the rare earth oxides displaying hydrophobic (>90°) advancing contact angle behavior at long times (>4 days). The results indicate that REOs are in fact hydrophilic when clean and become hydrophobic due to hydrocarbon adsorption. Furthermore, this study provides insight into how REOs can be used to promote stable dropwise condensation, which is important for the development of enhanced phase change surfaces.

  7. On the effects of magnetic bonding in rare earth transition metal intermetallics

    SciTech Connect

    Kumar, R.; Bentley, J. ); Yelon, W.B. . Research Reactor Facility)

    1990-01-01

    Neutron diffraction experiments on rare-earth transition metal magnetic alloys Er{sub 2}Fe{sub 14}B and Er{sub 2}Fe{sub 17} have been carried out at temperature above and below the ordering temperature ({Tc}). An anomalously large magnetic moment is observed at the crystallographic j{sub 2} site in Er{sub 2}Fe{sub 14}B which is the intersection point of the major ligand lines in the crystal structure. The interatomic Fe-Fe distances are in the range of strong ferromagnetic bonds ({ge} 2.66 {angstrom}). The analogous f site in Er{sub 2}Fe{sub 17} does not develop as large a magnetic moment. In addition, the same sites show strong preference for Fe atoms in the respective substituted compounds. Due to poor phase stability of Er{sub 2} (Co{sub x}Fe{sub 1 {minus}x}){sub 14}B compounds, iron substitution has been studied in detail in Er{sub 2}(Co{sub x}Fe{sub 1 {minus}x}){sub 17} alloys for site specific order an lattice distortion effects. However, a nonlinear change in the c lattice parameter observed in the neutron diffraction results cannot be explained on the basis of site preference alone. The neutron refinement results indicate iron rich compositions in Er{sub 2}(Co{sub x}Fe{sub 1 {minus}x}){sub 17} materials, which is related to random substitution of Fe dumbbell pairs in the rare earth sites in the lattice. However, extensive electron microscopy (selected area electron diffraction and high resolution imaging) of Er{sub 2}Fe{sub 17} and Er{sub 2}(Co{sub .40}Fe{sub .60}) {sub 17} failed to reveal any microscopic inhomogeneity. 12 refs., 5 figs., 2 tabs.

  8. DataStreme Earth's Climate System: Building a Climate Literate Society through Effective Partnerships

    NASA Astrophysics Data System (ADS)

    Brey, J. A.; Geer, I. W.; Weinbeck, R. S.; Mills, E. W.; Nugnes, K. A.; Stimach, A. E.

    2015-12-01

    Effective partnerships are key to increasing climate and overall environmental literacy. Financial support from NSF, NASA, and NOAA has allowed the American Meteorological Society (AMS) to offer DataStreme courses for almost 20 years. DataStreme Atmosphere, Ocean, and Earth's Climate System (ECS) are offered each fall and spring semester by Local Implementation Teams (LITs) across the country in coordination with AMS Education Program scientists and educators who develop instructional materials, provide logistical support to the LITs, and administer the project. A long-standing partnership with State University of New York's The College at Brockport gives teachers the opportunity to receive 3 tuition-free graduate credits upon successful completion of each DataStreme course and construction of a Plan of Action for educational peer-training. DataStreme ECS investigates the fundamental science of Earth's climate system, explores humans' impact on it, and identifies actions needed in response to climate change. The course provides participants with the knowledge to make informed climate decisions. In fact, according to a recent three-year study conducted by AMS, 98% of DataStreme ECS participants reported an increase in environmental literacy as a result of the course. DataStreme Atmosphere, Ocean, and ECS content has been improved because of AMS partnerships with NOAA and NASA. Specifically, hundreds of NASA and NOAA scientists and faculty from numerous institutions both domestic and abroad have contributed and reviewed DataStreme ECS content. Additional collaborations with Consortium for Ocean Leadership and the U.S. Ice Drilling Program greatly improved the course's paleoclimate content. Looking ahead, the Climate Resilience Toolkit from NOAA's Climate Program Office will further bolster the course this fall. These partnerships have resulted in a powerful, content-rich climate science course for K-12 teachers, building the foundation to a climate literate society.

  9. K-20 educator collaboration effective at conveying EarthScope science to middle school teachers

    NASA Astrophysics Data System (ADS)

    Pratt-Sitaula, B.; Butler, R. F.; Whitman, J. M.; Granshaw, F. D.; Groom, R.; Hedeen, C.; Magura, B.; Thompson, D.; Johnson, J. A.

    2010-12-01

    Teachers on the Leading Edge (TOTLE) program has developed an innovative model for middle school teacher professional development workshops that has proven effective at improving teacher knowledge of Pacific Northwest plate margin hazards and EarthScope science as well as leading to high rates of subsequent curriculum implementation. The key elements which appear to have led to the successes are: 1) facilitation team with broad content and educator expertise from K-12 master teachers and community college instructors to university and research scientists; 2) regional team format which encourages development of learning communities to continue past the workshop end; and 3) extensive “kit” of teaching materials for easy transfer to the classroom. The 1-week workshops were conducted during the summers of 2008-2010 and included 35 Pacific Northwest middle school teachers and 5 community college (or similar) regional team leaders each year. Content sessions and field trips were conducted by geoscientists from universities and research institutions (USGS, IRIS, UNAVCO, etc.). Teaching implementation sessions were conducted by K-12 master Earth science teachers. Approximately 10% of workshop costs were devoted to teaching material “kits” for all participants. Teacher confidence on workshop content topics increased on a 4-point scale (1 = “not at all confident”; 4 = “very confident”) from 2.7 to 3.2 to 3.7 on pre, immediately-post, and 8-month follow up surveys, respectively. Teacher performance on a content test improved an average of 19% after the workshop. Greater than 75% of teachers implemented at least 6 of the curricular elements in the year following the workshop. More concrete linking of the most complex topics (Ex. Cascadia GPS) to simpler elements led to improved implementation of those difficult curricular topics between 2008 and 2009 (Ex. from 28% to 40% implementation).

  10. Quantifying fractured crystalline-rock properties using well tests, earth tides and barometric effects

    NASA Astrophysics Data System (ADS)

    Burbey, Thomas J.; Hisz, David; Murdoch, Lawrence C.; Zhang, Meijing

    2012-01-01

    SummaryCharacterization of fractured rock aquifers often requires the acquisition and analysis of diverse datasets obtained from various instrumentation configurations. In this investigation at the fractured rock research site in Floyd County, Virginia, a high-precision borehole extensometer and tiltmeter were used during pumping to monitor deformation in the vicinity of fractures identified from borehole logging. Strain data obtained from earth tide analyses were used with the extensometer and tiltmeter data to quantify hydromechanical properties, including fracture volumetric specific storage, porosity, Poisson's ratio, the drained formation elastic modulus, and the effective dip direction of the fracture. Borehole tiltmeter data were used to estimate deformation caused by an aquifer test consisting of three pumping and recovery periods performed in well EX-1. During each period of the aquifer test the extensometer, located in W-03 and 27.7 m from the pumping well, was anchored over 2-m-long sections of (1) a fracture in hydraulic communication with EX-1, (2) a fracture that is not hydraulically connected with EX-1, and (3) an unfractured portion of bedrock directly above the hydraulically connected fracture. Results from the pumping tests yielded compressibilities of 1.3 × 10 -11 Pa -1, and 1.7 × 10 -11 Pa -1 for the lower and upper fractures, respectively. When coupled with areal strain calculated from earth tide analyses the volumetric specific storage values are 3.2 × 10 -11 Pa -1, and 2.8 × 10 -11 Pa -1 and the Poisson's ratios are 0.26 and 0.31, respectively. Using this with a calculated barometric efficiency of 0.45 allows for porosity calculations of 0.02 and 0.03, respectively for the vicinity of fractures in well W-03.

  11. Climatic effects of cloud particles in the atmospheres of Earth-like extrasolar planets

    NASA Astrophysics Data System (ADS)

    Kitzmann, D.; Patzer, A. B. C.; von Paris, P.; Grenfell, L.; Rauer, H.

    2008-09-01

    ABSTRACT Clouds can have an important effect on the climate (and thereby also on the habitability) of terrestrial planets. While clouds in the upper atmosphere increase atmospheric cooling by scattering of the incoming stellar radiation, clouds in the lower atmosphere are leading to an enhanced greenhouse effect, resulting in higher surface temperatures. Due to the shortage of observational detail regarding the atmospheres of terrestrial extrasolar planets, particular studies of clouds are limited to basic questions about the predominant processes at work, which have to be adressed. In this contribution we focus on the climatic effects of water droplet distributions in the lower tropospheres of Earth-like extrasolar planets. As a first approximation, parametrized distribution functions are used in our study for the description of the cloud particles. The distribution function used here is the log-normal distribution, which is known to be a good approximation to observed size spectra of cumulus clouds in the Earths atmosphere (cf. [3]). This size distribution function is given by the expression f(a) = N p 2? a ln ?g exp ? -(ln a - ln an)2 2(ln ?g)2 ? (1) and depends on the three parameters: particle number concentration N, geometric standard deviation ?g and the median radius an. The particle radius is denoted by a, respectively. Our simplified cloud description scheme is coupled with a one-dimensional radiative-convective climate-model (see e.g. [4] and [2] for a general overview of the model) in order to study the basic effects on the climate. Optical properties of the cloud particles are, thereby, calculated by Mie-theory (cf. e.g. [1]), assuming spherical particles composed of pure liquid water and have been included in the models radiative transfer scheme. Results for e.g. different types of central stars are presented and compared with the respective cloud-free situations. References [1] C.F. Bohren and D.R. Huffman, Absorption and scattering of light by small

  12. Bidirectional Spectral Reflectance of Earth Resources: Influence of Scene Complexity and Atmospheric Effects on Remote Sensing

    NASA Technical Reports Server (NTRS)

    Diner, D. J.

    1984-01-01

    Practical methods for remote sensing when scene complexity and atmospheric effects modify intrinsic reflective properties are developed. The radiation history from ground to space of light reflected from individual leaves is initially multiply scattered within the crop canopy, whose geometry provides a controlling influence, then scattered and attenuated as a result of transmission through the Earth's atmosphere. The experimental and theoretical tools for studying these effects quantitatively are under development. A new radiative transfer code which uses Fourier transforms to solve the 3-D equation of transfer was developed. The initial version permits inhomogeneous non-Lambertian surfaces but assumes horizontal uniformity for the atmosphere. The computational results are in excellent agreement with Monte Carlo calculations. Laboratory apparatus to study the variation of spectral reflectance of individual leaves as a function of illumination incidence angle and reflection angle was used. These data can then be used in models to determine canopy scattering effects. Stress tests by observing leaf reflectance at 0.9 microns as a function of time following clipping from the stem was performed. A reflectance increase due to loss of water has been observed.

  13. Potential Effects of Heliogeophysical Activity on the Dynamics of Sudden Cardiac Death at Earth Middle Latitudes

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.; Babayev, E.; Mustafa, F.

    2017-01-01

    Limited studies exist on comparing the possible effects of heliogeophysical activity (solar and geomagnetic) on the dynamics of sudden cardiac death (SCD) as a function of latitude on Earth. In this work we continue our earlier studies concerning the changing space environment and SCD dynamics at middle latitudes. The study covered 25 to 80-year old males and females, and used medical data provided by all emergency and first medical aid stations in the Grand Baku Area, Azerbaijan. Data coverage includedthe second peak of Solar Cycle 23 and its descending activity years followed by its long-lasting minimum. Gradation of geomagnetic activity into six levels was introduced to study the effect of space weather on SCD. The ANalysis Of VAriance (ANOVA) test was applied to study the significance of the geomagnetic activity effect, estimated by different geomagnetic indices, on SCD dynamics. Variations inthe number of SCDs occurring on days preceding and following the development of geomagnetic storms were also studied. Results revealed that the SCD number was largest on days of very low geomagnetic activity and on days proceeding and following geomagnetic storms with different intensities. Vulnerability for males was found to be higher around days of major and severe geomagnetic storms. Females, on the other hand, were more threatened around days of lower intensity storms. It is concluded that heliogeophysical activity could be considered as one of the regulating external/environmental factors in human homeostasis.

  14. Acaricidal effect of different diatomaceous earth formulations against Tyrophagus putrescentiae (Astigmata: Acaridae) on stored wheat.

    PubMed

    Iatrou, Styliani A; Kavallieratos, Nickolas G; Palyvos, Nickolas E; Buchelos, Constantin T; Tomanović, Snezana

    2010-02-01

    Laboratory bioassays were conducted to evaluate the effect of different diatomaceous earth (DE) formulations against adults and immature stages of the stored-product mite species Tyrophagus putrescentiae (Schrank). Five DE formulations were used in the tests: SilicoSec, PyriSec, Insecto, Protect-It, and DEA-P. The tests were conducted at 25 degrees C and 75% RH, on wheat, Triticum aestivum L., treated with DEs at two dose rates, 0.2 and 0.5 g/kg. The mortality of mite individuals was measured after 5 d of exposure, and after 30 d the treated wheat was checked for T. putrescentiae offspring. Significant differences were noted among the DEs tested. Application of the lowest dose rate (0.2 g/kg) provided mortality of both adults and immatures that exceeded 78%, whereas the respective data for 0.5 g/kg were almost in all cases 100%. The adults of T. putrescentiae were more tolerant to DEs than the immature stages. Generally, PyriSec was the most effective against adults. Progeny production was dramatically reduced with the increase of dose. The results of the present work indicate that T. putrescentiae can be effectively controlled by DEs on wheat, at dose rates as low as 0.2 g/kg.

  15. The effect of clouds on the earth's solar and infrared radiation budgets

    NASA Technical Reports Server (NTRS)

    Herman, G. F.; Wu, M.-L. C.; Johnson, W. T.

    1980-01-01

    The effect of global cloudiness on the solar and infrared components of the earth's radiation balance is studied in general circulation model experiments. A wintertime simulation is conducted in which the cloud radiative transfer calculations use realistic cloud optical properties and are fully interactive with model-generated cloudiness. This simulation is compared to others in which the clouds are alternatively non-interactive with respect to the solar or thermal radiation calculations. Other cloud processes (formation, latent heat release, precipitation, vertical mixing) were accurately simulated in these experiments. It is concluded that on a global basis clouds increase the global radiation balance by 40 W/sq m by absorbing longwave radiation, but decrease it by 56 W/sq m by reflecting solar radiation to space. The net cloud effect is therefore a reduction of the radiation balance by 16 W/sq m, and is dominated by the cloud albedo effect. Changes in cloud frequency and distribution and in atmospheric and land temperatures are also reported for the control and for the non-interactive simulations. In general, removal of the clouds' infrared absorption cools the atmosphere and causes additional cloudiness to occur, while removal of the clouds' solar radiative properties warms the atmosphere and causes fewer clouds to form. It is suggested that layered clouds and convective clouds over water enter the climate system as positive feedback components, while convective clouds over land enter as negative components.

  16. Effects of rare earth elements on the distribution of mineral elements and heavy metals in horseradish.

    PubMed

    Wang, Lihong; Huang, Xiaohua; Zhou, Qing

    2008-09-01

    In order to investigate the effects of rare earth elements (REEs) on horseradish, the distribution of the mineral elements and heavy metals in different organs of horseradish have been studied by using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Meanwhile, three variable major parameters, namely the concentration of REEs, the type of REEs, and the growth stage of plant were chosen. The results indicated that the test REEs, Ce(III) and Tb(III), could be accumulated in leaves, stems and roots of horseradish. In addition, we found that the content of mineral elements was increased in horseradish treated with 20mgl(-1) of Ce(III), but not those with the 20mgl(-1) of Tb(III). Moreover, the content of mineral elements in horseradish was decreased with the increasing concentration of REEs (100, 300mgl(-1)). Furthermore, we found that there were the opposite effects on the content of the heavy metals in horseradish treated with REEs. Finally, we found that the effect of REEs on the accumulation of REEs, and the content of mineral elements or heavy metals of horseradish during vigorous growth stage, no matter positive or negative, was more obvious than that of the other growth stages. These results demonstrated that the distribution behaviors of mineral elements and heavy metals in horseradish can be affected by the type and concentration of REEs, and the growth period of plant.

  17. Low-Earth orbit effects on organic composite materials flown on LDEF

    NASA Technical Reports Server (NTRS)

    George, Pete E.; Dursch, Harry W.

    1993-01-01

    Over 35 different types of organic matrix composites were flown as part of 11 different experiments onboard the NASA Long Duration Exposure Facility (LDEF) satellite. This materials and systems experiment satellite flew in low-earth orbit (LEO) for 69 months. For that period, the experiments were subjected to the LEO environment including atomic oxygen (AO), ultraviolet (UV) radiation, thermal cycling, microvacuum, meteoroid and space debris (M&D), and particle radiation. Since retrieval of the satellite in January of 1990, the principal experiment investigators have been deintegrating, examining, and testing the materials specimens flown. The most detrimental environmental effect on all organic matrix composites was material loss due to AO erosion. AO erosion of uncoated organic matrix composites (OMC) facing the satellite ram direction was responsible for significant mechanical property degradations. Also, thermal cycling-induced microcracking was observed in some nonunidirectional reinforced OMC's. Thermal cycling and outgassing caused significant but predictable dimensional changes as measured in situ on one experiment. Some metal and metal oxide-based coatings were found to be very effective at preventing AO erosion of OMC's. However, M&D impacts and coating fractures which compromised these coatings allowed AO erosion of the underlying OMC substrates. The findings for organic matrix composites flown on the LDEF are summarized and the LEO environmental factors, their effects, and the influence on space hardware design factors for LEO applications are identified.

  18. Bidirectional Spectral Reflectance of Earth Resources: Influence of Scene Complexity and Atmospheric Effects on Remote Sensing

    NASA Technical Reports Server (NTRS)

    Diner, D. J.

    1984-01-01

    Practical methods for remote sensing when scene complexity and atmospheric effects modify intrinsic reflective properties are developed. The radiation history from ground to space of light reflected from individual leaves is initially multiply scattered within the crop canopy, whose geometry provides a controlling influence, then scattered and attenuated as a result of transmission through the Earth's atmosphere. The experimental and theoretical tools for studying these effects quantitatively are under development. A new radiative transfer code which uses Fourier transforms to solve the 3-D equation of transfer was developed. The initial version permits inhomogeneous non-Lambertian surfaces but assumes horizontal uniformity for the atmosphere. The computational results are in excellent agreement with Monte Carlo calculations. Laboratory apparatus to study the variation of spectral reflectance of individual leaves as a function of illumination incidence angle and reflection angle was used. These data can then be used in models to determine canopy scattering effects. Stress tests by observing leaf reflectance at 0.9 microns as a function of time following clipping from the stem was performed. A reflectance increase due to loss of water has been observed.

  19. The effects of geomagnetic disturbances on electrical systems at the earth's surface

    NASA Astrophysics Data System (ADS)

    Boteler, D. H.; Pirjola, R. J.; Nevanlinna, H.

    Geomagnetic disturbances have affected electrical systems on the ground for over 150 years. The first effects were noted on the early telegraph in the 1840s and in this century magnetic storms have caused power system blackouts and phone system outages. Affected systems include all those that use electrical conductors: whether for transmission of power or signals or where the conducting properties are incidental to their use such as with pipelines and railway tracks. In power systems geomagnetically induced currents cause partial saturation of power transformers producing transformer heating and distortion of the ac waveform leading to misoperation of relays and other equipment. On pipelines, induced currents may contribute to corrosion but also present a problem with the electrical surveys of the pipe performed to monitor the corrosion prevention systems. Severity of these effects depends on disturbance size, proximity to the auroral zone, and the conductivity structure of the Earth. Also significant are system parameters such as the use of higher resistance coatings on pipelines and the linking of power systems into larger networks. In this paper we have attempted to catalogue all the published reports of geomagnetic effects on electrical systems and show their occurrence in the context of the solar cycle and geomagnetic activity variations for the years 1844 to 1996.

  20. The effect of clouds on the earth's solar and infrared radiation budgets

    NASA Technical Reports Server (NTRS)

    Herman, G. F.; Wu, M.-L. C.; Johnson, W. T.

    1980-01-01

    The effect of global cloudiness on the solar and infrared components of the earth's radiation balance is studied in general circulation model experiments. A wintertime simulation is conducted in which the cloud radiative transfer calculations use realistic cloud optical properties and are fully interactive with model-generated cloudiness. This simulation is compared to others in which the clouds are alternatively non-interactive with respect to the solar or thermal radiation calculations. Other cloud processes (formation, latent heat release, precipitation, vertical mixing) were accurately simulated in these experiments. It is concluded that on a global basis clouds increase the global radiation balance by 40 W/sq m by absorbing longwave radiation, but decrease it by 56 W/sq m by reflecting solar radiation to space. The net cloud effect is therefore a reduction of the radiation balance by 16 W/sq m, and is dominated by the cloud albedo effect. Changes in cloud frequency and distribution and in atmospheric and land temperatures are also reported for the control and for the non-interactive simulations. In general, removal of the clouds' infrared absorption cools the atmosphere and causes additional cloudiness to occur, while removal of the clouds' solar radiative properties warms the atmosphere and causes fewer clouds to form. It is suggested that layered clouds and convective clouds over water enter the climate system as positive feedback components, while convective clouds over land enter as negative components.

  1. On the variation of cometary coma brightness with comet-Earth distance (the Delta Effect)

    NASA Astrophysics Data System (ADS)

    Hughes, D. W.; McBride, N.; Boswell, J.; Jalowiczor, P.

    1993-07-01

    This paper investigates the Delta Effect, a term that is taken to cover the quantitative variation of observed cometary brightness as a function of comet-Earth distance, Delta (as opposed to the more restricted definition, where it specifically applies to deviations of this variation from the inverse-square law). We investigate the Delta Effect in a variety of ways. Opik's assumption, that the eye integrates over a fixed solid angle, is questioned. A CCD image of Comet Halley (1986 III), taken using the Anglo-Australian 3.9-m reflector, is used to quantify the true variation of the integrated brightness as a function of R, the radial distance in the plane of the sky between the center of brightness of the coma and the point being observed. It is found that the quantity k varies as a function of the solid angle over which the detector integrates. These changes in k also vary as a function of Delta. These findings are applied to recent observation of Comet Halley. Observations of the apparent magnitude of Comet Encke, obtained between 1838 and the present, are analyzed. It is concluded that the area of sky over which the eye integrates cometary coma brightness is not constant, and that the generally accepted paradigm, that the only effect on the observed cometary brightness of changing observer-comet distance is the usual inverse-square law, is generally true.

  2. Investigation of Strategies to Promote Effective Teacher Professional Development Experiences in Earth Science

    ERIC Educational Resources Information Center

    Engelmann, Carol A.

    2014-01-01

    This dissertation serves as a call to geoscientists to share responsibility with K-12 educators for increasing Earth science literacy. When partnerships are created among K-12 educators and geoscientists, the synergy created can promote Earth science literacy in students, teachers, and the broader community. The research described here resulted in…

  3. Perceived Barriers and Strategies to Effective Online Earth and Space Science Instruction

    ERIC Educational Resources Information Center

    Pottinger, James E.

    2012-01-01

    With the continual growth and demand of online courses, higher education institutions are attempting to meet the needs of today's learners by modifying and developing new student centered services and programs. As a result, faculty members are being forced into teaching online, including Earth and Space science faculty. Online Earth and Space…

  4. Perceived Barriers and Strategies to Effective Online Earth and Space Science Instruction

    ERIC Educational Resources Information Center

    Pottinger, James E.

    2012-01-01

    With the continual growth and demand of online courses, higher education institutions are attempting to meet the needs of today's learners by modifying and developing new student centered services and programs. As a result, faculty members are being forced into teaching online, including Earth and Space science faculty. Online Earth and Space…

  5. Investigation of Strategies to Promote Effective Teacher Professional Development Experiences in Earth Science

    ERIC Educational Resources Information Center

    Engelmann, Carol A.

    2014-01-01

    This dissertation serves as a call to geoscientists to share responsibility with K-12 educators for increasing Earth science literacy. When partnerships are created among K-12 educators and geoscientists, the synergy created can promote Earth science literacy in students, teachers, and the broader community. The research described here resulted in…

  6. Seismic Effects on the Design of Geosynthetic-Reinforced Earth Retaining Structures

    DTIC Science & Technology

    1998-07-01

    geosynthetics and are subjected to cyclic motion such as that caused by earthquakes. It will examine some case studies of the performance of... geosynthetic reinforced earth retaining structures (GSRW) and review some time tested concepts dealing with both geosynthetics and seismic earth pressures

  7. Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

    PubMed

    Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

    2015-01-01

    Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  8. Difluorenyl carbo-Benzenes: Synthesis, Electronic Structure, and Two-Photon Absorption Properties of Hydrocarbon Quadrupolar Chromophores.

    PubMed

    Baglai, Iaroslav; de Anda-Villa, Manuel; Barba-Barba, Rodrigo M; Poidevin, Corentin; Ramos-Ortíz, Gabriel; Maraval, Valérie; Lepetit, Christine; Saffon-Merceron, Nathalie; Maldonado, José-Luis; Chauvin, Remi

    2015-09-28

    The synthesis, crystal and electronic structures, and one- and two-photon absorption properties of two quadrupolar fluorenyl-substituted tetraphenyl carbo-benzenes are described. These all-hydrocarbon chromophores, differing in the nature of the linkers between the fluorenyl substituents and the carbo-benzene core (C-C bonds for 3 a, C-C=C-C expanders for 3 b), exhibit quasi-superimposable one-photon absorption (1PA) spectra but different two-photon absorption (2PA) cross-sections σ2PA. Z-scan measurements (under NIR femtosecond excitation) indeed showed that the C≡C expansion results in an approximately twofold increase in the σ2PA value, from 336 to 656 GM (1 GM = 10(-50) cm(4) s molecule(-1) photon(-1)) at λ = 800 nm. The first excited states of Au and Ag symmetry accounting for 1PA and 2PA, respectively, were calculated at the TDDFT level of theory and used for sum-over-state estimations of σ2PA(λi), in which λi = 2 hc/Ei, h is Planck's constant, c is the speed of light, and Ei is the energy of the 2PA-allowed transition. The calculated σ2PA values of 227 GM at 687 nm for 3 a and 349 GM at 708 nm for 3 b are in agreement with the Z-scan results.

  9. Research on Earth's rotation and the effect of atmospheric pressure on vertical deformation and sea level variability

    NASA Technical Reports Server (NTRS)

    Wahr, John

    1993-01-01

    The work done under NASA grant NAG5-485 included modelling the deformation of the earth caused by variations in atmospheric pressure. The amount of deformation near coasts is sensitive to the nature of the oceanic response to the pressure. The PSMSL (Permanent Service for Mean Sea Level) data suggest the response is inverted barometer at periods greater than a couple months. Green's functions were constructed to describe the perturbation of the geoid caused by atmospheric and oceanic loading and by the accompanying load-induced deformation. It was found that perturbation of up to 2 cm are possible. Ice mass balance data was used for continental glaciers to look at the glacial contributions to time-dependent changes in polar motion, the lod, the earth's gravitational field, the position of the earth's center-of-mass, and global sea level. It was found that there can be lateral, non-hydrostatic structure inside the fluid core caused by gravitational forcing from the mantle, from the inner core, or from topography at the core/mantle or inner core/outer core boundaries. The nutational and tidal response of a non-hydrostatic earth with a solid inner core was modeled. Monthly, global tide gauge data from PSMSL was used to look at the 18.6-year ocean tide, the 14-month pole tide, the oceanic response to pressure, the linear trend and inter-annual variability in the earth's gravity field, the global sea level rise, and the effects of post glacial rebound. The effects of mantle anelasticity on nutations, earth tides, and tidal variation in the lod was modeled. Results of this model can be used with Crustal Dynamics observations to look at the anelastic dissipation and dispersion at tidal periods. The effects of surface topography on various components of crustal deformation was also modeled, and numerical models were developed of post glacial rebound.

  10. Effect of thickness of liquefiable foundation on the seismic performance of earth dams

    NASA Astrophysics Data System (ADS)

    Berhe, Tensay; Wu, Wei

    2010-05-01

    Earthquake induced liquefaction continues to be a major threat to many civil engineering structures on the earth. Among these structures are earthfill dams. There are two major causes for the seismically inadequacy of a statically stable earthfill dams around the world. These are the liquefaction of the foundation layer and shell of the dams. In order to gain a better understanding of the seismic performance of earthfill dams on liquefiable foundation layer, a numerical model of an earthfill dam with mixed clay core founded on a liquefiable foundation subjected to earthquake is being studied. The properties and thickness of the liquefiable layer are varied to determine the related effects on the overlying earthfill dam. In order to explore the effect of the varying depth and thickness of liquefiable layer on the seismic response of earthfill dams, the total foundation thickness is divided into three equal layers so that the properties of each layer can be varied and studied. A finite difference numerical code, FLAC3D is used during the study. Results and discussions related to the significance of the depth and thickness of liquefiable layer in the foundation and resulting damage to the earthfill dam and hence the seismic performance of earthfill dam are presented. Keywords: Earthquake, liquefaction, earthfill dams, seismic performance, varying depth.

  11. Effect of Rare Earth Elements on Isothermal Transformation Kinetics in Si-Mn-Mo Bainite Steels

    NASA Astrophysics Data System (ADS)

    Liang, Yilong; Yi, Yanliang; Long, Shaolei; Tan, Qibing

    2014-12-01

    Isothermal heat treatments to Si-Mn-Mo steel specimens were performed, and time-temperature-transformation curves (C-curves) were plotted by DIL805A/D differential dilatometer. The effect of rare earth (RE) elements on bainite transformation kinetics was systematically studied by adopting the empirical electron theory of solids and molecules, Johnson-Mehl-Avrami equation calculation, dilatometry, and metallography. Experimental results show that the addition of RE in Si-Mn-Mo bainite steels leads to the C-curves moving to bottom right and prolongs incubation period of bainite transformation. Moreover, RE addition increases the values of phase structure factors ( n A, F {C/D}) and activation energy of bainite transformation, inhibits the formation of granular bainite, and refines microstructures of bainitic ferrite and substructures. During the bainite transformation process, bainite transformation is delayed due to the drag effect, which is induced by the segregation of RE at the ferrite interphase and the retardation of Fe-C-RE (segregation units) on carbon diffusion.

  12. Effects of space plasma discharge on the performance of large antenna structures in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Blume, Hans-Juergen C.

    1987-01-01

    The anomalous plasma around spacecrafts in low Earth orbit represents the coma of an artificial comet. The plasma discharge is caused by an energetic disturbance of charged particles which were formerly in a state of equilibrium. The plasma can effect the passive and active radio frequency operation of large space antennas by inducing corona discharge or strong arcing in the antenna feeds. One such large space antenna is the 15-meter hoop column antenna which consists of a mesh membrane material (tricot knitted gold plated wire) reflector and carbon fiber tension cords. The atomic oxygen in the plasma discharge state can force the wire base metal particles through the gold lattice and oxydize the metal particles to build a Schottky-barrier contact at the point where the wires meet. This effect can cause strong deviations in the reflector performance in terms of antenna pattern and losses. Also, the carbon-fiber cords can experience a strength reduction of 30 percent over a 40-hour exposure time.

  13. Oblate-Earth Effects on the Calculation of Ec During Spacecraft Reentry

    NASA Technical Reports Server (NTRS)

    Bacon, John B.; Matney, Mark J.

    2017-01-01

    The bulge in the Earth at its equator has been shown to lead to a clustering of natural decays biased to occur towards the equator and away from the orbit's extreme latitudes. Such clustering must be considered when predicting the Expectation of Casualty (Ec) during a natural decay because of the clustering of the human population in the same lower latitudes. This study expands upon prior work, and formalizes the correction that must be made to the calculation of the average exposed population density as a result of this effect. Although a generic equation can be derived from this work to approximate the effects of gravitational and atmospheric perturbations on a final decay, such an equation averages certain important subtleties in achieving a best fit over all conditions. The authors recommend that direct simulation be used to calculate the true Ec for any specific entry as a more accurate method. A generic equation is provided, represented as a function of ballistic number and inclination of the entering spacecraft over the credible range of ballistic numbers.

  14. Evaluation of Low Earth Orbit Environmental Effects on International Space Station Thermal Control Materials

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Rutledge, Sharon K.; Hasegawa, Mark M.; Reed, Charles K.

    1998-01-01

    Samples of International Space Station (ISS) thermal control coatings were exposed to simulated low Earth orbit (LEO) environmental conditions to determine effects on optical properties. In one test, samples of the white paint coating Z-93P were coated with outgassed products from Tefzel(R) (ethylene tetrafluoroethylene copolymer) power cable insulation as-may occur on ISS. These samples were then exposed, along with an uncontaminated Z-93P witness sample, to vacuum ultraviolet (VUV) radiation to determine solar absorptance degradation. The Z-93P samples coated with Tefzel(R) outgassing products experienced greater increases in solar absorptance than witness samples not coated with Tefzel(R) outgassing products. In another test, samples of second surface silvered Teflon(R) FEP (fluorinated ethylene propylene), SiO. (where x=2)-coated silvered Teflon(R) FEP, and Z-93P witness samples were exposed to the combined environments of atomic oxygen and VLTV radiation to determine optical properties changes due to these simulated ISS environmental effects. This test verified the durability of these materials in the absence of contaminants.

  15. Evaluation of Low-Earth-Orbit Environmental Effects on International Space Station Thermal Control Materials

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.

    1998-01-01

    Many spacecraft thermal control coatings in low Earth orbit (LEO) can be affected by solar ultraviolet radiation and atomic oxygen. Ultraviolet radiation can darken some polymers and oxides commonly used in thermal control materials. Atomic oxygen can erode polymer materials, but it may reverse the ultraviolet-darkening effect on oxides. Maintaining the desired solar absorptance for thermal control coatings is important to assure the proper operating temperature of the spacecraft. Thermal control coatings to be used on the International Space Station (ISS) were evaluated for their performance after exposure in the NASA Lewis Research Center's Atomic Oxygen-Vacuum Ultraviolet Exposure (AO-VUV) facility. This facility simulated the LEO environments of solar vacuum ultraviolet (VUV) radiation (wavelength range, 115 to 200 nanometers (nm)) and VUV combined with atomic oxygen. Solar absorptance was measured in vacuo to eliminate the "bleaching" effects of ambient oxygen on VUV-induced degradation. The objective of these experiments was to determine solar absorptance increases of various thermal control materials due to exposure to simulated LEO conditions similar to those expected for ISS. Work was done in support of ISS efforts at the requests of Boeing Space and Defense Systems and Lockheed Martin Vought Systems.

  16. The effect of the earth's radiation belts on an optical system.

    PubMed

    Wolff, C

    1966-11-01

    A photoelectric optical imaging system has survived one year in the earth's radiation belts with no measurable (<20%) change in sensitivity. The system passes through all of the radiation belts twice every 64 hr, and experiences a noise level equivalent to 400 photons/sec when in their most intense regions. While this noise is far less than that of other photoelectric systems operating in the belts because of the small effective area of the photocathode, the noise per unit cathode area is 1.3 x 10(5) photons/sec-cm(2), and is similar to the best of the other systems. The number and energy distribution of incident particles is calculated and then combined with shielding estimates to give the total energy absorbed in the optical elements. Radiation damage reports in the literature are shown to be consistent with the lack of a sensitivity change in this orbiting optical system. The effects of particle radiation on optical systems in general is briefly summarized, with emphasis on recent work of others.

  17. Effect of rare-earth-dopants on Bragg gratings recording in PTR glasses

    NASA Astrophysics Data System (ADS)

    Nikonorov, N. V.; Ivanov, S. A.; Kozlova, D. A.; Pichugin, I. S.

    2017-05-01

    In present paper, we represent a study on the effect of RE dopants (lanthanum, erbium, ytterbium, and neodymium) on the process of the photo-thermo-induced (PTI) crystallization. During this work, we investigated each step of the PTI crystallization process including silver particle formation, growth of shell and nanocrystal. To perform these observations, we reduced the temperature of thermal treatment below the glass transition temperature to slow down all processes inside the glass. We found out that the silver nanoparticles formation process does not depend from the concentration of RE ions and is the same as in case of the parent PTR glass. In other hand the growth kinetics of AgBr-NaBr shell and NaF nanocrystals differ from the parent glass and depend on RE concentration. Our observations show no difference in final position of plasmon resonance, which means that the PTI crystallization process itself stays the same and is not affected by the RE dopants. Further study shows that utmost achievable refractive index change falls off with rare earth dopant concentration increase mainly due to the bond formed between dopant and fluorine. This bond prevents fluorine from participation in crystallization process thus overall volume fraction of the crystalline phase decreases. This effect can be corrected by addition of fluorine in the chemical composition of the glass at the synthesis. In conclusion, we show that refractive index change in doped glass with appropriate concentration of additional fluorine is same as in the parent glass (1500 ppm).

  18. The Effects of Solar Maximum on the Earth's Satellite Population and Space Situational Awareness

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2012-01-01

    The rapidly approaching maximum of Solar Cycle 24 will have wide-ranging effects not only on the number and distribution of resident space objects, but also on vital aspects of space situational awareness, including conjunction assessment processes. The best known consequence of high solar activity is an increase in the density of the thermosphere, which, in turn, increases drag on the vast majority of objects in low Earth orbit. The most prominent evidence of this is seen in a dramatic increase in space object reentries. Due to the massive amounts of new debris created by the fragmentations of Fengyun-1C, Cosmos 2251 and Iridium 33 during the recent period of Solar Minimum, this effect might reach epic levels. However, space surveillance systems are also affected, both directly and indirectly, historically leading to an increase in the number of lost satellites and in the routine accuracy of the calculation of their orbits. Thus, at a time when more objects are drifting through regions containing exceptionally high-value assets, such as the International Space Station and remote sensing satellites, their position uncertainties increase. In other words, as the possibility of damaging and catastrophic collisions increases, our ability to protect space systems is degraded. Potential countermeasures include adjustments to space surveillance techniques and the resetting of collision avoidance maneuver thresholds.

  19. Gravity effects on sediment sorting: limitations of models developed on Earth for Mars

    NASA Astrophysics Data System (ADS)

    Kuhn, N. J.; Kuhn, B.; Gartmann, A.

    2015-10-01

    Most studies on surface processes on planetary bodies assume that the use of empirical models developed for Earth is possible if the mathematical equations include all the relevant factors, such as gravity, viscosity and the density of water and sediment. However, most models for sediment transport on Earth are at least semi-empirical, using coefficients to link observed sediment movement to controlling factors such as flow velocity, slope and channel dimensions. However, using roughness and drag coefficients, as well as parameters describing incipient motion of particles, observed on Earth on another planet, violates, strictly speaking, the boundary conditions set for their application by fluid dynamics because the coefficienst describe a flow condition, not a particle property. Reduced gravity affects the flow around a settling partcile or over the bed of a watercourse, therefore data and models from Earth do not apply to another planet. Comparing observations from reduced gravity experiments and model results obtained on Earth confirm the significance of this error, e.g. by underestimating settling velocities of sandy particles by 10 to 50% for Mars when using models from Earth. In this study, the relevance of this error is examined by simulating the sorting of sediment deposited from water flowing on Mars. The results indicate that sorting on Mars is less pronounced than models calibrated on Earth suggest. This has implications for the selection of landing sites and,more importantly, the identification of strata potentially bearing traces of past life during rover missions on Mars. try, 2001

  20. Gravity effects on sediment sorting: limitations of models developed on Earth for Mars

    NASA Astrophysics Data System (ADS)

    Kuhn, Nikolaus J.; Kuhn, Brigitte; Gartmann, Andres

    2015-04-01

    Most studies on surface processes on planetary bodies assume that the use of empirical models developed for Earth is possible if the mathematical equations include all the relevant factors, such as gravity, viscosity and the density of water and sediment. However, most models for sediment transport on Earth are at least semi-empirical, using coefficients to link observed sediment movement to controlling factors such as flow velocity, slope and channel dimensions. However, using roughness and drag coefficients, as well as parameters describing incipient motion of particles, observed on Earth on another planet, violates, strictly speaking, the boundary conditions set for their application by fluid dynamics because the coefficienst describe a flow condition, not a particle property. Reduced gravity affects the flow around a settling partcile or over the bed of a watercourse, therefore data and models from Earth do not apply to another planet. Comparing observations from reduced gravity experiments and model results obtained on Earth confirm the significance of this error, e.g. by underestimating settling velocities of sandy particles by 10 to 50% for Mars when using models from Earth. In this study, the relevance of this error is examined by simulating the sorting of sediment deposited from water flowing on Mars. The results indicate that sorting on Mars is less pronounced than models calibrated on Earth suggest. This has implications for the selection of landing sites and, more importantly, the identification of strata potentially bearing traces of past life during rover missions on Mars.

  1. The Effect of Gender on the Attitudes of Undergraduates toward Young-Earth Creationism after Enrollment in an Origins Course

    ERIC Educational Resources Information Center

    Vinaja, Sean Stephen

    2016-01-01

    Many Christian students graduate from secondary schools and enter Christian colleges with worldviews that are unbiblical or contain unbiblical components, many of which stem from their beliefs regarding origins. Little research has been done to study the effect of gender on the role of a young-earth creationist (YEC) origins course in shaping…

  2. The Effect of Gender on the Attitudes of Undergraduates toward Young-Earth Creationism after Enrollment in an Origins Course

    ERIC Educational Resources Information Center

    Vinaja, Sean Stephen

    2016-01-01

    Many Christian students graduate from secondary schools and enter Christian colleges with worldviews that are unbiblical or contain unbiblical components, many of which stem from their beliefs regarding origins. Little research has been done to study the effect of gender on the role of a young-earth creationist (YEC) origins course in shaping…

  3. Earth's rotation variations effect the earthquake triggering and lithospheric plates movement

    NASA Astrophysics Data System (ADS)

    Ostrihansky, Lubor

    2013-04-01

    The first group of scientists claims that the headline stated above is quite absurd because the Earth's rotation variations exert the pressure only ~1 Pa on the lithosphere. The second group claims that the despinning of the axial Earth's rotation only influences not determines the plate motion and earthquake triggering. However the third possibility is correct. The Earth's rotation variations cause the earthquake triggering and the plate movement as many observations can prove. Comparison with neighboring planets shows that Mars has no plate movement owing to the absence of large tidal forming body and Venus has slow rotation and negligible flattening. It is not true that tidal forces acting on the Earth are insufficient. Tidal forces acting on the Earth's flattening cause sufficient northward directing torques acting on plates comparable in magnitudes with the seismic moments. The westward movement of plates is evident but its calculation is more difficult and it is necessary to suppose that both the acceleration and deceleration of the Earth's rotation cause the westward lithosphere movement. Many statistics prove the coincidence of earthquakes with semidiurnal tides as result of mid-ocean ridges formation owing to the material fatigue and by loading of waters in subduction zones. Coincidence of earthquakes with LOD variations extremes resulting in Earth moment of inertia changes owing to the tidal deformation and other coincidences with factors influencing the Earth's rotation as 8.45 years Moon perigee rotation and 18.63 years nodal variation present next proofs. The last confirmation follows from the earthquake repetitions in 19 years Metonic cycle. But claims that the plate movement is caused by the mantle convection or by inhomogenities in the mantle or even by the Earth's expansions are easily disprovable conjectures.

  4. Study of the effect of cloud inhomogeneity on the earth radiation budget experiment

    NASA Technical Reports Server (NTRS)

    Smith, Phillip J.

    1988-01-01

    The Earth Radiation Budget Experiment (ERBE) is the most recent and probably the most intensive mission designed to gather precise measurements of the Earth's radiation components. The data obtained from ERBE is of great importance for future climatological studies. A statistical study reveals that the ERBE scanner data are highly correlated and that instantaneous measurements corresponding to neighboring pixels contain almost the same information. Analyzing only a fraction of the data set when sampling is suggested and applications of this strategy are given in the calculation of the albedo of the Earth and of the cloud-forcing over ocean.

  5. The effect on Earth's surface temperature from variations in rotation rate, continent formation, solar luminosity, and carbon dioxide.

    PubMed

    Kuhn, W R; Walker, J C; Marshall, H G

    1989-08-20

    Proposed evolutionary histories of solar luminosity, atmospheric carbon dioxide amounts, Earth rotation rate, and continent formation have been used to generate a time evolution of Earth's surface temperature. While speculative because of uncertainties in the input parameters, such a study does help to prioritize the areas of most concern to paleoclimatic research while illustrating the relationships and mutual dependencies. The mean temperature averages about 5 K higher than today over most of geologic time; the overall variation is less than 15 K. The evolution of Earth's rotation rate makes a significant contribution to the surface temperature distribution as late as 0.5 b.y. ago. While there is little change in equatorial temperatures, polar temperatures decrease, being some 15 K lower 3.5 b.y. ago than with present day rotation. The effect of continent growth on albedo is of secondary importance.

  6. Effect of rare earth filtration on patient exposure, dose reduction, and image quality in oral panoramic radiology

    SciTech Connect

    Tyndall, D.A.; Washburn, D.B.

    1987-01-01

    Rare earth intensifying screen material (Gd2O2S:Tb) was added to the standard Al filtration of an oral panoramic x-ray unit, resulting in a beam capable of achieving reductions in patient dose without a loss of image quality. The added rare earth filtration technique resulted in patient dose reductions of 21-56%, depending on anatomic sites, when compared to the conventional Al filtration technique. Films generated from both techniques were measured densitometrically and evaluated by a panel of practicing clinicians. Diagnostically significant differences were minimal. The results indicate that use of rare earth filters in oral panoramic radiography is an effective means of reducing exposures of dental patients to ionizing radiation.

  7. Effects of trapped proton flux anisotropy on dose rates in low Earth orbit.

    PubMed

    Badhwar, G D; Kushin, V V; Akatov YuA; Myltseva, V A

    1999-06-01

    Trapped protons in the South Atlantic Anomaly (SAA) have a rather narrow pitch angle distribution and exhibit east-west anisotropy. In low Earth orbits, the E-W effect results in different amounts of radiation dose received by different sections of the spacecraft. This effect is best studied on missions in which the spacecraft flies in a fixed orientation. The magnitude of the effect depends on the particle energy and altitude through the SAA. In this paper, we describe a clear example of this effect from measurements of radiation dose rates and linear energy transfer spectra made on Space Shuttle flight STS-94 (28.5 degree inclination x 296 km altitude). The ratio of dose rates from the two directions at this location in the mid-deck was 2.7. As expected from model calculations, the spectra from the two directions are different, that is the ratio is energy dependent. The data can be used to distinguish the anisotropy models. The flight carried an active tissue equivalent proportional counter (TEPC), and passive thermoluminscent detectors (TLDs), and two types of nuclear emulsions. Using nuclear emulsions, charged particles and secondary neutron energy spectra were measured. The combined galactic cosmic radiation+trapped charged particle lineal energy spectra measured by the TEPC and the linear energy transfer spectrum measured by nuclear emulsions are in good agreement. The charged particle absorbed dose rates varied from 112 to 175 microGy/day, and dose equivalent rates from 264.3 to 413 microSv/day. Neutrons in the 1-10 MeV contributed a dose rate of 3.7 microGy/day and dose equivalent rate of 30.8 microSv/day, respectively.

  8. Rare earth elements (REEs): effects on germination and growth of selected crop and native plant species.

    PubMed

    Thomas, Philippe J; Carpenter, David; Boutin, Céline; Allison, Jane E

    2014-02-01

    The phytotoxicity of rare earth elements (REEs) is still poorly understood. The exposure-response relationships of three native Canadian plant species (common milkweed, Asclepias syriaca L., showy ticktrefoil, Desmodium canadense (L.) DC. and switchgrass, Panicum virgatum L.) and two commonly used crop species (radish, Raphanus sativus L., and tomato, Solanum lycopersicum L.) to the REEs lanthanum (La), yttrium (Y) and cerium (Ce) were tested. In separate experiments, seven to eight doses of each element were added to the soil prior to sowing seeds. Effects of REE dose on germination were established through measures of total percent germination and speed of germination; effects on growth were established through determination of above ground biomass. Ce was also tested at two pH levels and plant tissue analysis was conducted on pooled samples. Effects on germination were mostly observed with Ce at low pH. However, effects on growth were more pronounced, with detectable inhibition concentrations causing 10% and 25% reductions in biomass for the two native forb species (A. syriaca and D. canadense) with all REEs and on all species tested with Ce in both soil pH treatments. Concentration of Ce in aboveground biomass was lower than root Ce content, and followed the dose-response trend. From values measured in natural soils around the world, our results continue to support the notion that REEs are of limited toxicity and not considered extremely hazardous to the environment. However, in areas where REE contamination is likely, the slow accumulation of these elements in the environment could become problematic. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. Effects of polar ice on the earth's rotation and gravitational potential

    NASA Technical Reports Server (NTRS)

    Trupin, Andrew S.

    1993-01-01

    The contributions of the Antarctic and the Greenland ice sheets to the earth's gravity, displacement, and rotation are estimated using gridded values of the net surface accumulation rates in the ice sheets of these two regions. It is found that the contributions to the low-order zonal harmonic coefficients of the earth's gravitational potential from Antarctica are between 2 and 10 times larger than the uncertainties of the zonal harmonics derived from satellite solutions; for Greenland, the coefficients are within an order of magnitude of the uncertainties of the satellite solutions. Polar contributions to the displacement of the center of mass of the solid earth, as seen in the frame of reference of satellites tracked from the earth surface, range from less than 1 mm to 1.5 cm over a 60-yr period.

  10. Earth Resources

    ERIC Educational Resources Information Center

    Brewer, Tom

    1970-01-01

    Reviews some of the more concerted, large-scale efforts in the earth resources areas" in order to help the computer community obtain insights into the activities it can jointly particpate in withthe earth resources community." (Author)

  11. Effect of the Earth's inner structure on the gravity in definitions of height systems

    NASA Astrophysics Data System (ADS)

    Tenzer, Robert; Foroughi, Ismael; Pitoňák, Martin; Šprlák, Michal

    2017-01-01

    SUMMARYIn context of the vertical datum unification, the geoid-to-quasigeoid separation has been of significant interest in recent years, because most of existing local vertical datums are realized in the system of either normal or orthometric heights. Nevertheless, the normal-orthometric heights are still used in many other countries where the normal gravity values along leveling lines were adopted instead of the observed gravity. Whereas the conversion between the orthometric and normal heights is defined by means of the mean gravity disturbances (i.e., differences between the mean values of the actual and normal gravity) along the plumbline within the topography, differences between the normal and normal-orthometric heights can be described by means of the surface gravity disturbances. Since the normal gravity field does not reflect the topographic masses and actual mass density distribution inside the <span class="hlt">Earth</span>, the definition of gravity represents a principal aspect for a realization of particular vertical datum. To address this issue in this study we investigate <span class="hlt">effects</span> of the <span class="hlt">Earth</span>'s inner density structure on the surface and mean gravity disturbances, and discuss their impact on the vertical datum realization. These two gravity field quantities are computed globally with a spectral resolution complete to a spherical harmonic degree 2160 using the global gravity, terrain, ice-thickness, inland bathymetry and crustal structure models. Our results reveal that both, the surface and mean gravity disturbances mostly comprise the gravitational signal of topography and masses distributed below the geoid surface. Moreover, in polar areas a significant contribution comes from large glaciers. In contrast, the contributions of anomalous density distribution within the topography attributed to major lakes, sediments and bedrock density variations are much less pronounced. We also demonstrate that the mean gravity disturbances within the topography are significantly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1810i0012W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1810i0012W"><span>New estimates of the <span class="hlt">Earth</span> radiation budget under cloud-free conditions and cloud radiative <span class="hlt">effects</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wild, Martin; Hakuba, Maria Z.; Folini, Doris; Schär, Christoph; Long, Charles</p> <p>2017-02-01</p> <p>In previous studies1, 2 we derived new estimates for the magnitude of the components of the global mean energy budget using to the extent possible the information contained in direct observations from surface and space. Here we establish complementary estimates for the global mean energy budget specifically under cloud-free conditions. The energy fluxes under cloud-free conditions at the Top of Atmosphere (TOA) can be determined with high accuracy from satellite measurements (CERES-EBAF). For the estimation of their counterparts at the <span class="hlt">Earth</span>'s surface we follow the approach presented in our recent studies, based on an analysis of 39 state of the art global climate models from CMIP5 and their bias structure compared to a comprehensive set of high quality surface observations from the Baseline Surface Radiation Network (BSRN). Thereby we infer a best estimate of 249 Wm-2 for the global mean clear-sky downward shortwave radiation at the surface, and a corresponding clear-sky surface shortwave absorption of 216 Wm-2, considering a global mean surface albedo of 13 %. Combined with a best estimate for the global mean net shortwave influx at the TOA under cloud-free skies from CERES-EBAF of 287 Wm-2, this leaves an amount of 71 Wm-2 absorbed shortwave radiation in the cloud-free atmosphere. The 71 Wm-2 coincide with our earlier estimate for this quantity in Wild et al. (2006)3 based on older models and fewer direct observations, suggesting that this estimate is fairly robust. For the clear-sky downward longwave radiation at the <span class="hlt">Earth</span> surface we obtain a best estimate of 314 Wm-2. A comparison of the clear-sky global energy balance diagram presented here with the corresponding all-sky diagram established in our previous studies enables a quantification of the global mean shortwave, longwave and net cloud-radiative <span class="hlt">effects</span> at the TOA, within the atmosphere and at the surface, as well as an assessment of their representation in climate models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoJI.209..297T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.209..297T"><span><span class="hlt">Effect</span> of the <span class="hlt">Earth</span>'s inner structure on the gravity in definitions of height systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tenzer, Robert; Foroughi, Ismael; Pitoňák, Martin; Šprlák, Michal</p> <p>2017-04-01</p> <p>In context of the vertical datum unification, the geoid-to-quasi-geoid separation has been of significant interest in recent years, because most of existing local vertical datums are realized in the system of either normal or orthometric heights. Nevertheless, the normal-orthometric heights are still used in many other countries where the normal gravity values along leveling lines were adopted instead of the observed gravity. Whereas the conversion between the orthometric and normal heights is defined by means of the mean gravity disturbances (i.e. differences between the mean values of the actual and normal gravity) along the plumbline within the topography, differences between the normal and normal-orthometric heights can be described by means of the surface gravity disturbances. Since the normal gravity field does not reflect the topographic masses and actual mass density distribution inside the <span class="hlt">Earth</span>, the definition of gravity represents a principal aspect for a realization of particular vertical datum. To address this issue in this study, we investigate <span class="hlt">effects</span> of the <span class="hlt">Earth</span>'s inner density structure on the surface and mean gravity disturbances, and discuss their impact on the vertical datum realization. These two gravity field quantities are computed globally with a spectral resolution complete to a spherical harmonic degree 2160 using the global gravity, terrain, ice-thickness, inland bathymetry and crustal structure models. Our results reveal that both, the surface and mean gravity disturbances mostly comprise the gravitational signal of topography and masses distributed below the geoid surface. Moreover, in polar areas, a significant contribution comes from large glaciers. In contrast, the contributions of anomalous density distribution within the topography attributed to major lakes, sediments and bedrock density variations are much less pronounced. We also demonstrate that the mean gravity disturbances within the topography are significantly modified</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T43F2735C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T43F2735C"><span>The <span class="hlt">effects</span> of continental block configuration on the <span class="hlt">Earth</span>'s heat loss</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cooper, C. M.; Moresi, L. N.; Lenardic, A.</p> <p>2012-12-01</p> <p>The presence of continents on the <span class="hlt">Earth</span>'s surface produces an unusual convective system with parallel mechanisms for losing internal heat: conduction through the stable, continental insulating lid, and a more efficient balance of horizontal advection and vertical conduction in the actively overturning oceanic thermal boundary layer. The resulting thermal network which describes the heat loss behavior of the combined mechanisms can create a buffer which moderates the insulating <span class="hlt">effect</span> of the continental lid on the <span class="hlt">Earth</span>'s overall heat loss, but only if the deep mantle flow communicates between sub-continental and sub-oceanic regions. If communication is disconnected between the two heat transfer mechanisms, then the continent locally insulates the mantle beneath it causing the subcontinental mantle temperature to increase compared to the sub-oceanic mantle setting the stage for a different global impact on mantle dynamics. The thermal-network theory which describes the two end-member cases does not directly constrain the cross-over between these states; however, the configuration of the insulating lid is expected to play a major role. Here we extend previous 2D work to include multiple continental blocks in various configurations to determine when the mixed-network theory holds and when thermal isolated modes can be produced. The continental blocks were arranged in three configurations while holding the total surface area covered by the blocks constant. The three possible layouts were: (1) a single block centered in the model domain, (2) two blocks of equal size centered in the model domain or (3) four blocks of equal size centered in the 3x3x1 Cartesian model domain. All continental blocks are fixed to the coordinate system; when apart (in the two or four block configuration), the blocks do not move relative to each other, but the mantle is free to move dynamically in all directions via periodic boundary conditions. The total surface area covered by continental</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003RSTEd..21..265M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003RSTEd..21..265M"><span>A study of students' perceptions of the organisation and <span class="hlt">effectiveness</span> of fieldwork in <span class="hlt">earth</span> sciences education</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marques, Luis; Praia, Joa¨O.; Kempa, Richard</p> <p>2003-02-01</p> <p>This paper reports the findings of a preliminary evaluation of an in-service training programme designed for practising geology/<span class="hlt">earth</span> science teachers in Portuguese high schools and intended to enhance the <span class="hlt">effectiveness</span> of fieldwork activities organised by them for their students. Among the points particularly stressed during the in-service training were that students should be adequately prepared for fieldwork through classroom-based activities prior to the fieldwork itself and that to arrive at the maximum educational benefit for the students, they should be involved in collaborative group-based investigation. The findings, derived from an enquiry among students following their exposure to fieldwork, revealed that in both these aspects teachers failed to put theory into practice, probably as the result of a lack of confidence to implement novel procedures. On the positive side, the students reported that they enjoyed the social interaction with other students that the fieldwork made possible and the opportunity to work independently of the teachers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E..36A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E..36A"><span><span class="hlt">Effects</span> of DeOrbitSail as applied to Lifetime predictions of Low <span class="hlt">Earth</span> Orbit Satellites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Afful, Andoh; Opperman, Ben; Steyn, Herman</p> <p>2016-07-01</p> <p>Orbit lifetime prediction is an important component of satellite mission design and post-launch space operations. Throughout its lifetime in space, a spacecraft is exposed to risk of collision with orbital debris or operational satellites. This risk is especially high within the Low <span class="hlt">Earth</span> Orbit (LEO) region where the highest density of space debris is accumulated. This paper investigates orbital decay of some LEO micro-satellites and accelerating orbit decay by using a deorbitsail. The Semi-Analytical Liu Theory (SALT) and the Satellite Toolkit was employed to determine the mean elements and expressions for the time rates of change. Test cases of observed decayed satellites (Iridium-85 and Starshine-1) are used to evaluate the predicted theory. Results for the test cases indicated that the theory fitted observational data well within acceptable limits. Orbit decay progress of the SUNSAT micro-satellite was analysed using relevant orbital parameters derived from historic Two Line Element (TLE) sets and comparing with decay and lifetime prediction models. This paper also explored the deorbit date and time for a 1U CubeSat (ZACUBE-01). The use of solar sails as devices to speed up the deorbiting of LEO satellites is considered. In a drag sail mode, the deorbitsail technique significantly increases the <span class="hlt">effective</span> cross-sectional area of a satellite, subsequently increasing atmospheric drag and accelerating orbit decay. The concept proposed in this study introduced a very useful technique of orbit decay as well as deorbiting of spacecraft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1728b0421S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1728b0421S"><span>Mixed alkali <span class="hlt">effect</span> on the spectroscopic properties of alkali-alkaline <span class="hlt">earth</span> oxide borate glasses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Srinivas, G.; Ramesh, B.; Shareefuddin, Md.; Chary, M. N.; Sayanna, R.</p> <p>2016-05-01</p> <p>The mixed alkali and alkaline <span class="hlt">earth</span> oxide borate glass with the composition xK2O - (25-x) Li2O-12.5BaO-12.5MgO-50B2O3 (x = 0, 5, 10, 15, 20 and 25mol %) and doped with 1mol% CuO were prepared by the melt quenching technique. From the optical absorption spectra the optical band gap, electronic polarizability(α02-), interaction parameter (A), theoretical and experimental optical basicity (Λ) values were evaluated. From the Electron Paramagnetic Resonance (EPR) spectral data the number of spins (N) and susceptibility (χ) were evaluated. The values of (α02-), and (Λ) increases with increasing of K2O content and electronic polarizability and interaction parameter show opposite behaviuor which may be due to the creation of non-bridging oxygens and expansion of borate network. The reciprocal of susceptibility (1/χ) and spin concentration (N) as a function of K2O content, varied nonlinearly which may be due to creation of non-bridging oxygens in the present glass system. This may be attributed to mixed alkali <span class="hlt">effect</span> (MAE).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870064690&hterms=Chandler+Wobble&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DChandler%2BWobble','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870064690&hterms=Chandler+Wobble&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DChandler%2BWobble"><span>Snow load <span class="hlt">effect</span> on <span class="hlt">earth</span>'s rotation and gravitational field, 1979-1985</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chao, B. Fong; O'Connor, William P.; Chang, Alfred T. C.; Hall, Dorothy K.; Foster, James L.</p> <p>1987-01-01</p> <p>A global, monthly snow depth data set has been generated from the Nimbus 7 satellite observations using passive microwave remote-sensing techniques. Seven years of data, 1979-1985, are analyzed to compute the snow load <span class="hlt">effects</span> on the <span class="hlt">earth</span>'s rotation and low-degree zonal gravitational field. The resultant time series show dominant seasonal cycles. The annual peak-to-peak variation in J2 is found to be 2.3 x 10 to the -10th, that in J3 to be 1.1 x 10 to the -10th, and believed to decrease rapidly for higher degrees. The corresponding change in the length of day is 41 micro-s. The annual wobble excitation is (4.9 marc sec, -109 deg) for the prograde motion component and (4.8 marc sec, -28 deg) for the retrograde motion component. The excitation power of the Chandler wobble due to the snow load is estimated to be about 25 dB less than the power needed to maintain the observed Chandler wobble.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SSCom.252...51N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SSCom.252...51N"><span>Crystal electric field <span class="hlt">effects</span> and thermal expansion of rare-<span class="hlt">earth</span> hexaborides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Novikov, V. V.; Pilipenko, E. S.; Bud'ko, S. L.</p> <p>2017-02-01</p> <p>Anomalies in the magnetic contribution to the thermal expansion coefficients ∆β(T)of the CeB6, PrB6, and NdB6 hexaborides in the range of 5-300 K were found by comparison with diamagnetic LaB6. The characteristic of the anomalies was the same in all the studied borides: a distinct peak at low temperatures, followed by a broad maximum at higher temperatures (50-100 K), then a decrease and transition to the region of negative values as the temperature increases further. The features of ∆β(T) are explained by the <span class="hlt">effects</span> of the magnetic order (sharp low temperature peaks) and the crystal electric field (CEF). The βCEF(T) dependencies were calculated using Raman and neutron scattering data on the splitting of the rare-<span class="hlt">earth</span> (RE) ions R3+ f-level by the CEF. A satisfactory consistency between the values of βCEF(T) and ∆β(T)was obtained for the studied hexaborides. Additionally, we determined the values of the Grüneisen parameter γi that correspond to the transition between the ground and excited multiplets of R3+ ions f-level splitting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870064690&hterms=gravitational+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dgravitational%2Bfield','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870064690&hterms=gravitational+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dgravitational%2Bfield"><span>Snow load <span class="hlt">effect</span> on <span class="hlt">earth</span>'s rotation and gravitational field, 1979-1985</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chao, B. Fong; O'Connor, William P.; Chang, Alfred T. C.; Hall, Dorothy K.; Foster, James L.</p> <p>1987-01-01</p> <p>A global, monthly snow depth data set has been generated from the Nimbus 7 satellite observations using passive microwave remote-sensing techniques. Seven years of data, 1979-1985, are analyzed to compute the snow load <span class="hlt">effects</span> on the <span class="hlt">earth</span>'s rotation and low-degree zonal gravitational field. The resultant time series show dominant seasonal cycles. The annual peak-to-peak variation in J2 is found to be 2.3 x 10 to the -10th, that in J3 to be 1.1 x 10 to the -10th, and believed to decrease rapidly for higher degrees. The corresponding change in the length of day is 41 micro-s. The annual wobble excitation is (4.9 marc sec, -109 deg) for the prograde motion component and (4.8 marc sec, -28 deg) for the retrograde motion component. The excitation power of the Chandler wobble due to the snow load is estimated to be about 25 dB less than the power needed to maintain the observed Chandler wobble.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930030078&hterms=type+energy&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtype%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930030078&hterms=type+energy&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtype%2Benergy"><span>The <span class="hlt">effect</span> of cloud type on <span class="hlt">earth</span>'s energy balance - Results for selected regions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ockert-Bell, Maureen E.; Hartmann, Dennis L.</p> <p>1992-01-01</p> <p>International Satellite Cloud Climatology Project (ISCCP) C1 cloud information is compared with planetary albedo, outgoing longwave radiation (OLR), and net radiation measured at the top of the atmosphere by the <span class="hlt">Earth</span> Radiation Budget Experiment (ERBE). Principal component analysis indicates that the day-to-day variations of the abundances of the 35 cloud types of the C1 data are correlated with each other, so that for many purposes the data set can be well represented by about five cloud types. Using stepwise multiple regression, the ISCCP C1 data can be used to predict the day-to-day variations of the energy balance measured by ERBE for 2.5-deg regions. Total fractional area coverage of cloudiness is a relatively poor predictor of radiation budget quantities. If the total fractional area coverage by clouds is divided into contributions from several distinct cloud types, the fractional coverages by these several cloud types will together form a much better prediction of radiation budget quantities than the single variable of total fractional-area cloud coverage. The regression equations can be used to estimate the net <span class="hlt">effect</span> of clouds on the radiation balance and the contributions from particular types of clouds to albedo, OLR, and net radiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17748704','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17748704"><span><span class="hlt">Effects</span> of the Large June 1975 Meteoroid Storm on <span class="hlt">Earth</span>'s Ionosphere.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kaufmann, P; Kuntz, V L; Leme, N M; Piazza, L R; Boas, J W; Brecher, K; Crouchley, J</p> <p>1989-11-10</p> <p>The June 1975 meteoroid storm detected on the moon by the Apollo seismometers was the largest ever observed. Reexamination of radio data taken at that time showed that the storm also produced pronounced disturbances on <span class="hlt">Earth</span>, which were recorded as unique phase anomalies on very low frequency (VLF) radio propagation paths in the low terrestrial ionosphere. Persistent <span class="hlt">effects</span> were observed for the major storm period (20 to 30 June 1975), including reductions in the diurnal phase variation, advances in the nighttime and daytime phase levels, and reductions in the sunset phase delay rate. Large nighttime phase advances, lasting a few hours, were detected on some days at all VLF transmissions, and for the shorter propagation path they were comparable to solar Lyman alpha daytime ionization. Ion production rates attributable to the meteor storm were estimated to be about 0.6 to 3.0 ions per centimeter cubed per second at the E and D regions, respectively. The storm was a sporadic one with a radiant (that is, the point of apparent origin in the sky) located in the Southern Hemisphere, with a right ascension 1 to 2 hours larger than the sun's right ascension.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4025297','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4025297"><span>The insecticidal <span class="hlt">effect</span> of diatomaceous <span class="hlt">earth</span> against adults and nymphs of Blattella germanica</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hosseini, Seyyed Akbar; Bazrafkan, Sahar; Vatandoost, Hassan; Abaei, Mohammad Reza; Ahmadi, Mussa Soleimani; Tavassoli, Maryam; Shayeghi, Mansoreh</p> <p>2014-01-01</p> <p>Objective To evaluate the insecticidal <span class="hlt">effect</span> of diatomaceous <span class="hlt">earth</span> (DE) against adults and nymphs of Blattella germanica. Methods This cross sectional study has been done on the laboratory strain of German cockroaches. Two stages, nymph and adult, were exposed to six dose rates of the DE, 2.5, 5, 10, 15, 20 and 25 g/m2, at 24, 48 and 72 h exposure period. Mortality (number of dead cockroaches) was assessed after 24 h. Other exposed specimens were transferred to the beakers contained food and water for counting the retard mortality rate after 1 week. Results Increasing in dose rates of DE increased mortality rate, so that the lowest and highest mortality rates were observed in 2.5 and 25 g/m2, respectively. The results of the statistical analysis showed no significant difference in the lethality of 50% of DE plus water on the German cockroach nymphs. Conclusions Due to the resistance of German cockroach against organochloride, organophosphorus, carbamate and pyrethriodes insecticides, it is suggested to use DE for insect's control. PMID:25183087</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JRScT..40..545K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JRScT..40..545K"><span><span class="hlt">Effect</span> of knowledge integration activities on students' perception of the <span class="hlt">earth</span>'s crust as a cyclic system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kali, Yael; Orion, Nir; Eylon, Bat-Sheva</p> <p>2003-08-01</p> <p>Systems thinking is regarded as a high-order thinking skill required in scientific, technological, and everyday domains. However, little is known about systems thinking in the context of science education. In the current research, students' understanding of the rock cycle system after a learning program was characterized, and the <span class="hlt">effect</span> of a concluding knowledge integration activity on their systems thinking was studied. Answers to an open-ended test were interpreted using a systems thinking continuum, ranging from a completely static view of the system to an understanding of the system's cyclic nature. A meaningful improvement in students' views of the rock cycle toward the higher side of the systems thinking continuum was found after the knowledge integration activity. Students became more aware of the dynamic and cyclic nature of the rock cycle, and their ability to construct sequences of processes representing material transformation in relatively large chunks significantly improved. Success of the knowledge integration activity stresses the importance of postknowledge acquisition activities, which engage students in a dual process of differentiation of their knowledge and reintegration in a systems context. We suggest including such activities in curricula involving systems-based contents, particularly in <span class="hlt">earth</span> science, in which systems thinking can bring about environmental literacy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992RSPSA.438..467S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992RSPSA.438..467S"><span>A third-order theory for the <span class="hlt">effect</span> of drag on <span class="hlt">earth</span> satellite orbits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharma, Ram K.</p> <p>1992-09-01</p> <p>Analytical theory for the motion of near-<span class="hlt">earth</span> satellite orbits with the air drag <span class="hlt">effect</span> is developed in terms of the KS elements, utilizing an analytical oblate exponential atmospheric model. The series expansions include up to cubic terms in e (eccentricity) and c(a small parameter dependent on the flattening of the atmosphere). Due to the symmetry of the KS element equations, only one of the eight equations is integrated analytically to obtain the state vector at the end of each revolution. Numerical comparisons are made with nine test cases, selected to cover a wide range of eccentricity with perigee heights near to 300 km at three different inclinations. A comparison of three orbital parameters: semi-major axis, eccentricity and argument of perigee, perturbed by air drag with oblate atmosphere is made with the previously developed second-order theory. It is found that with the present theory with increase in eccentricity there is improvement in semi-major axis and eccentricity computations over the second-order theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830026135','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830026135"><span>A mathematical characterization of vegetation <span class="hlt">effect</span> on microwave remote sensing from the <span class="hlt">Earth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Choe, Y.; Tsang, L.</p> <p>1983-01-01</p> <p>In passive microwave remote sensing of the <span class="hlt">earth</span>, a theoretical model that utilizes the radiative transfer equations was developed to account for the volume scattering <span class="hlt">effects</span> of the vegetation canopy. Vegetation canopies such as alfalfa, sorghum, and corn are simulated by a layer of ellipsoidal scatterers and cylindrical structures. The ellipsoidal scatterers represent the leaves of vegetation and are randomly positioned and oriented. The orientation of ellipsoids is characterized by a probability density function of Eulerian angles of rotation. The cylindrical structures represent the stalks of vegetation and their radii are assumed to be much smaller than their lengths. The underlying soil is represented by a half-space medium with a homogeneous permittivity and uniform temperature profile. The radiative transfer quations are solved by a numerical method using a Gaussian quadrature formula to compute both the vertical and horizontal polarized brightness temperature as a function of observation angle. The theory was applied to the interpretation of experimental data obtained from sorghum covered fields near College Station, Texas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22606502','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22606502"><span>Mixed alkali <span class="hlt">effect</span> on the spectroscopic properties of alkali-alkaline <span class="hlt">earth</span> oxide borate glasses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Srinivas, G. Ramesh, B.; Shareefuddin, Md.; Chary, M. N.; Sayanna, R.</p> <p>2016-05-06</p> <p>The mixed alkali and alkaline <span class="hlt">earth</span> oxide borate glass with the composition xK{sub 2}O - (25-x) Li{sub 2}O-12.5BaO-12.5MgO-50B{sub 2}O{sub 3} (x = 0, 5, 10, 15, 20 and 25mol %) and doped with 1mol% CuO were prepared by the melt quenching technique. From the optical absorption spectra the optical band gap, electronic polarizability(α{sub 0}2-), interaction parameter (A), theoretical and experimental optical basicity (Λ) values were evaluated. From the Electron Paramagnetic Resonance (EPR) spectral data the number of spins (N) and susceptibility (χ) were evaluated. The values of (α{sub 0}2-), and (Λ) increases with increasing of K{sub 2}O content and electronic polarizability and interaction parameter show opposite behaviuor which may be due to the creation of non-bridging oxygens and expansion of borate network. The reciprocal of susceptibility (1/χ) and spin concentration (N) as a function of K{sub 2}O content, varied nonlinearly which may be due to creation of non-bridging oxygens in the present glass system. This may be attributed to mixed alkali <span class="hlt">effect</span> (MAE).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930030078&hterms=cloud+effect+earth+radiation+budget&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcloud%2Beffect%2Bearth%2Bradiation%2Bbudget','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930030078&hterms=cloud+effect+earth+radiation+budget&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcloud%2Beffect%2Bearth%2Bradiation%2Bbudget"><span>The <span class="hlt">effect</span> of cloud type on <span class="hlt">earth</span>'s energy balance - Results for selected regions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ockert-Bell, Maureen E.; Hartmann, Dennis L.</p> <p>1992-01-01</p> <p>International Satellite Cloud Climatology Project (ISCCP) C1 cloud information is compared with planetary albedo, outgoing longwave radiation (OLR), and net radiation measured at the top of the atmosphere by the <span class="hlt">Earth</span> Radiation Budget Experiment (ERBE). Principal component analysis indicates that the day-to-day variations of the abundances of the 35 cloud types of the C1 data are correlated with each other, so that for many purposes the data set can be well represented by about five cloud types. Using stepwise multiple regression, the ISCCP C1 data can be used to predict the day-to-day variations of the energy balance measured by ERBE for 2.5-deg regions. Total fractional area coverage of cloudiness is a relatively poor predictor of radiation budget quantities. If the total fractional area coverage by clouds is divided into contributions from several distinct cloud types, the fractional coverages by these several cloud types will together form a much better prediction of radiation budget quantities than the single variable of total fractional-area cloud coverage. The regression equations can be used to estimate the net <span class="hlt">effect</span> of clouds on the radiation balance and the contributions from particular types of clouds to albedo, OLR, and net radiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSA51B2423E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSA51B2423E"><span>A Study About the <span class="hlt">Effects</span> of Solar Variability on the <span class="hlt">Earth</span>'s Climate During Forbush Decrease Events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Echer, M. P. D. S.; Portugal, W.; Echer, E.; Abe Pacini, A.</p> <p>2016-12-01</p> <p>We present in this work a study about possible changes on the surface temperature during periods with decreased charged particle fluxes on the <span class="hlt">Earth</span>'s atmosphere, called Forbush Decreases (FD). The FDs are the events related with the Galactic Cosmic Rays (GCR) flux decreases on the atmosphere that occur due to solar energetic events, like Coronal Mass Ejections (CME). These energetic particles interact with atmospheric constituents and induce the ionization of the neutral atmosphere. It is known that the presence of ions on the troposphere can change the vapor condensation patterns, since some ions can behave like cloud condensation nuclei (CCN). So, there is a work hypothesis, that the GCR flux decreases can cause changes on the physical-chemical properties of the atmosphere. We have conducted a study to investigate these possible <span class="hlt">effects</span> around the ten strongest FD occurred from 1987 to 2015. GCR data are collected from Oulu neutron monitor and surface temperature data are obtained from NOAA - National Oceanic Atmospheric Administration / GSOD - Global Surface Summary of the Day. The variation of the daily mean surface temperature of several regions, including low, medium and high latitude stations, is investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.7641G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.7641G"><span>Open top culverts as an alternative drainage system to minimize ecological <span class="hlt">effects</span> in <span class="hlt">earth</span> roads.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>García, Jose L.; Elorrieta, Jose; Robredo, Jose C.; García, Ricardo; García, Fernando; Gimenez, Martin C.</p> <p>2013-04-01</p> <p>During the last fifteen years a research team from School of Forestry at the Technical University of Madrid (Spain) has developed several competitive research projects regarding forest roads and open top culverts. A first approach was established with a prototype of 7 meters length in a hydraulic channel at the laboratory determining main parameters of different open top culverts in relation to different sizes of gravels and the self washing properties relationship with different slopes up to 8 %. The curves obtained may help to properly install these drainage systems avoiding maintenance costs. In addition more targeted pilot studies were developed in different forest <span class="hlt">earth</span> roads in center and north Spain. The construction of the stations under study was financed by the U.P.M and the R&D National Plan. The main outcomes relates the low variation of humidity in a 20 m. wide range at both sides of the open top culverts and several considerations relating the angle of installation, the spacing of such drainage systems and the benefits against rilling along the roads. Also the erosion produced downhill was established and some construction methods to avoid adverse ecological <span class="hlt">effects</span>. The diffusion of results includes congresses and a small booklet with a great acceptance in forestry services. Also a patent (ES 2 262 437) of an advanced model has been registered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19364383','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19364383"><span><span class="hlt">Effect</span> of low doses of dietary rare <span class="hlt">earth</span> elements on growth performance of broilers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>He, M L; Wehr, U; Rambeck, W A</p> <p>2010-02-01</p> <p>The present study was designed to investigate <span class="hlt">effect</span> of dietary rare <span class="hlt">earth</span> elements (REE), including both organic and inorganic compounds, on growth performance of broilers. In experiment 1, a total of 180 male Ross broiler chicks were allocated to 72 pens with different assignment: four chicks per pen or individually. The following three treatment diets were applied: control, REE-chlorides at a dose of 40 mg/kg and REE-citrate at a dose of 70 mg/kg. Each treatment group had 24 pens containing both assignments (12 pens each). In experiment 2, a total of 72 male 3-day-old Ross broiler chicks were separated to four groups: control, REE-chlorides at a dose of 70 mg/kg and REE-citrate at doses of 70 mg/kg and 100 mg/kg. In experiment 1, dietary REE-citrate improved body weight gain during the overall period by 5.0% (p < 0.05) while the increase with REE-chloride was not significant. In experiment 2, growth <span class="hlt">effects</span> (p < 0.05) were only found in the period from day 21 to slaughter with all REE forms, and feed conversion ratio was improved by 3.4% (p < 0.05) with REE-citrate. No significant <span class="hlt">effects</span> of REE were found on chill weight, percentages of breast meat, thigh weight, drumstick weight and wing weight. Concentrations of La and Ce in the liver and muscles were very low, accounting for 0.11-0.76 and 0.02-0.30 mg/kg respectively. There was weak tendency for a dose-response relationship especially in the groups supplemented with REE-chlorides. The main blood serum biochemical parameters were not significantly affected by REE in the diets. The results suggest that dietary supplementation of low doses of REE-citrates might improve growth performance of broilers without affecting carcass composition and health of the broilers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986ASSL..127..129P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986ASSL..127..129P"><span>On the possibility of a 'cuckoo-<span class="hlt">effect</span>' in the <span class="hlt">earth</span>-moon system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pauwels, T.</p> <p></p> <p>In this paper an investigation is made of the possibility that the moon could have depleted the <span class="hlt">earth</span> satellite system of all natural satellites by a combination of orbit-orbit resonances and tidal evolution. Simulations show that for a satellite closer than 150 <span class="hlt">earth</span> radii, avoiding all resonances is definitely impossible, but it can be captured in a stable resonant orbit as well as in a resonant orbit leading to a close approach to the moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA549030','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA549030"><span>The <span class="hlt">Effects</span> of Rare <span class="hlt">Earth</span> Doping on Gallium Nitride Thin Films</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2011-09-01</p> <p>l D !J Date v 3o J\\CA.-~ 2olf Date AFIT/DS/ENP/11-S05 Abstract The thermal neutron capture cross section of the rare <span class="hlt">earth</span> metal isotope 157Gd...the trend of the rare <span class="hlt">earth</span> metal work function. The utility of gadolinium as a neutron detection material in a hypothetical direct conversion...44 2.4.2 Metal Induced Gap States Model . . . . . . . . . . . . . . . . . . . . . . . . . . 46 2.4.3 Current Transport in Schottky Barrier Devices</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMMR52A..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMMR52A..06M"><span>The <span class="hlt">Effect</span> of Nickel on the Seismic Wave Belocities of Iron at the Pressure Conditions of the <span class="hlt">Earth</span>'s Core</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martorell Masip, B.; Vocadlo, L.; Brodholt, J. P.; Wood, I.</p> <p>2011-12-01</p> <p>Understanding the physical properties of the <span class="hlt">Earth</span>'s core is a key step in the study of the evolution and dynamics of our planet. For much of the last century, based on studies of meteorites [1], it was believed that <span class="hlt">Earth</span>'s core was predominantly a mixture of iron and nickel. More specifically, the <span class="hlt">Earth</span>'s inner core is a solid Fe-Ni alloy at high temperature (T, 6000 K) and high pressure (P, 360 GPa). Furthermore, to account for the lower than expected density in the <span class="hlt">Earth</span>'s core, it has been suggested that light elements must also be present [2]. While the <span class="hlt">effect</span> of light elements on the properties of iron have been the subject of an extensive literature [3-6], the <span class="hlt">effect</span> of nickel on the properties of iron has often been overlooked; this is due to the expectation, based on their proximity in the periodic table, that the properties of Ni are sufficiently similar to those of iron that the presence of nickel can be neglected. Although recent research using high P-T experiments and theoretical studies of Fe-Ni alloys has been performed in order to establish whether nickel affects the physical properties of iron, the results have been inconclusive and sometimes contradictory [7-11]. Here we present a DFT study of the athermal elastic properties of solid Fe-Ni alloys at core pressures using the GGA. We have calculated the equation of state (EoS) for Fe-Ni alloys at several compositions for bcc, fcc and hcp structures, and fitted the results to Birch-Murnaghan 3rd order equations of state. We have also calculated the elastic constants for each structure at 360 GPa and evaluated the seismic wave velocities. Our results show that the <span class="hlt">effect</span> of small amounts of Ni is significant (-1.9% in vp and -4.0% in vs for hcp structure of Fe93.25-Ni6.75 alloy), and therefore nickel must be taken into account if a detailed model of the <span class="hlt">Earth</span>'s inner core is to be constructed. Other aspects of the influence of nickel, such as its <span class="hlt">effect</span> on the high P-T phase diagram and melting curve</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28294267','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28294267"><span>Nucleation-dependant chemical bonding paradigm: the <span class="hlt">effect</span> of rare <span class="hlt">earth</span> ions on the nucleation of urea in aqueous solution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Xiaoyan; Sun, Congting; Wu, Sixin; Xue, Dongfeng</p> <p>2017-03-29</p> <p>Rare <span class="hlt">earth</span> ions can be used to construct a variety of novel structures and are favorable to chemical bonding regulation and design. In this study, the chemical bonding paradigm between rare <span class="hlt">earth</span> ions (Ln(3+)) and urea molecules in an aqueous solution can be tracked by the evolution of C[double bond, length as m-dash]O, NH2, and CN vibration bands during the urea nucleation stage. Rare <span class="hlt">earth</span> ions such as La(3+), Gd(3+), and Lu(3+) can manipulate the nucleation time of urea via regulating the nucleation-dependant N-C[double bond, length as m-dash]OH-N hydrogen-bonding between urea molecules. Two types of chemical bondings between Ln(3+) and urea molecules have been confirmed, which are Ln(3+)O[double bond, length as m-dash]C-N and Ln(3+)NH2-C. Compared with Ln(3+)NH2-C, Ln(3+) prefers to coordinate with the O[double bond, length as m-dash]C bond in urea. With a higher concentration of rare <span class="hlt">earth</span> ions in the solution, some N-C[double bond, length as m-dash]OH-N hydrogen bonds are broken as a consequence of the incorporation of Ln(3+) into the lattice, resulting in the decreased symmetry of local urea molecules in the crystalline nuclei and the consequent Ln(3+) concentration-dependent nucleation time of urea. Moreover, using the ionic electronegativity scale of Ln(3+), the different <span class="hlt">effects</span> of La(3+), Gd(3+), and Lu(3+) on urea nucleation can be further distinguished. The present study provides basic data for unrevealing the chemical bonding regulation role of rare <span class="hlt">earth</span> ions in the formation of hydrogen bonded materials, which may give insight into the design and fabrication of novel materials utilizing rare <span class="hlt">earth</span> ions to adjust the chemical bonding process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AIPC.1542..281J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AIPC.1542..281J"><span><span class="hlt">Effect</span> of inter-particle rolling resistance on passive <span class="hlt">earth</span> pressure against a translating rigid retaining wall</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Mingjing; He, Jie; Liu, Fang; Wang, Huaning</p> <p>2013-06-01</p> <p>The presence of the inter-particle rolling resistance of soil grains results in higher bulk shear strength in the soil, which relates to the <span class="hlt">earth</span> pressure calculation based on the classic theory. This paper focuses on the <span class="hlt">effect</span> of the inter-particle rolling resistance on the <span class="hlt">earth</span> pressure against a rigid retaining wall. A particle contact model considering the inter-particle rolling resistance was implemented into the distinct element code PFC2D, which was then used to simulate a rigid wall retaining a sandy backfill. The passive <span class="hlt">earth</span> pressure against the wall subjected to a translational displacement was analyzed and compared with results without considering the inter-particle rolling resistance. The influence of the inter-particle rolling resistance was examined from the microscopic scale (e.g., averaged micro-pure rotation-rate) as well as the macroscopic scale (e.g., the magnitude and action point of resultant <span class="hlt">earth</span> pressures). The results show that the inter-particle rolling resistance of the backfill strongly affects the value of passive thrust behind the wall, but it has no significant <span class="hlt">effect</span> on the action position of the thrust. The distribution of micro-pure rotation-rate (APR) in the backfill provides an insight into the connection between inter-particle rolling resistance to the energy dissipation in the shear zone behind the wall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3367923','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3367923"><span><span class="hlt">Effect</span> of Rare <span class="hlt">Earth</span> Ions on the Properties of Composites Composed of Ethylene Vinyl Acetate Copolymer and Layered Double Hydroxides</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Lili; Li, Bin; Zhao, Xiaohong; Chen, Chunxia; Cao, Jingjing</p> <p>2012-01-01</p> <p>Background The study on the rare <span class="hlt">earth</span> (RE)-doped layered double hydroxides (LDHs) has received considerable attention due to their potential applications in catalysts. However, the use of RE-doped LDHs as polymer halogen-free flame retardants was seldom investigated. Furthermore, the <span class="hlt">effect</span> of rare <span class="hlt">earth</span> elements on the hydrophobicity of LDHs materials and the compatibility of LDHs/polymer composite has seldom been reported. Methodology/Principal Findings The stearate sodium surface modified Ni-containing LDHs and RE-doped Ni-containing LDHs were rapidly synthesized by a coprecipitation method coupled with the microwave hydrothermal treatment. The influences of trace amounts of rare <span class="hlt">earth</span> ions La, Ce and Nd on the amount of water molecules, the crystallinity, the morphology, the hydrophobicity of modified Ni-containing LDHs and the adsorption of modifier in the surface of LDHs were investigated by TGA, XRD, TEM, contact angle and IR, respectively. Moreover, the <span class="hlt">effects</span> of the rare <span class="hlt">earth</span> ions on the interfacial compatibility, the flame retardancy and the mechanical properties of ethylene vinyl acetate copolymer (EVA)/LDHs composites were also explored in detail. Conclusions/Significance S-Ni0.1MgAl-La displayed more uniform dispersion and better interfacial compatibility in EVA matrix compared with other LDHs. Furthermore, the S-Ni0.1MgAl-La/EVA composite showed the best fire retardancy and mechanical properties in all composites. PMID:22693627</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9915E..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9915E..08S"><span>The <span class="hlt">effect</span> of proton radiation on the EMCCD for a low <span class="hlt">Earth</span> orbit satellite mission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Ken; Daigle, Olivier; Scott, Alan; Piche, Louis; Hudson, Danya</p> <p>2016-08-01</p> <p>We report on the proton radiation <span class="hlt">effects</span> on a 1k x 1k e2v EMCCD utilized in the Nüvü EM N2 1024 camera. Radiation testing was performed at the TRIUMF Proton Irradiation Facility in Canada, where the e2v CCD201-20 EMCCD received a 105 MeV proton fluence up to 5.2x109 protons/cm2, emulating a 1 year's radiation dose of solar protons in low <span class="hlt">earth</span> orbit with nominal shielding that would be expected from a small or microsatellite. The primary space-based application is for Space Situational Awareness (SSA), where a small telescope images faint orbiting Resident Space Objects (RSOs) on the EMCCD, resulting in faint streaks at the photon level of signal in the images. Of particular concern is the <span class="hlt">effect</span> of proton radiation on low level CTE, where very low level signals could be severely impaired if not lost. Although other groups have reported on the characteristics of irradiated EMCCDs, their CTE results are not portable to this application. To understand the real impact of proton irradiation the device must be tested under realistic operating conditions with representative backgrounds, clock periods, and signal levels. Testing was performed both in the laboratory and under a night sky on the ground in order to emulate a complex star background environment containing RSOs. The degradation is presented and mitigation techniques are proposed. As compared to conventional CCDs, the EMCCD with high gain allows faint and moving RSOs to be detected with a relatively small telescope aperture, at improved signal to noise ratio at high frame rates. This allows the satellite platform to take sharp images immediately upon slewing to the target without the need for complex and relatively slow attitude stabilization systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B53K..05F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B53K..05F"><span>The <span class="hlt">effects</span> of rare <span class="hlt">earth</span> elements on an anaerobic hydrogen producing microorganism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujita, Y.; St Jeor, J. D.; Reed, D. W.</p> <p>2016-12-01</p> <p>Rapid growth of new energy technologies and consumer electronics is leading to increased fluxes of rare <span class="hlt">earth</span> elements (REE), during the phases of resource extraction, product usage, recycling, and disposal. However, little is known about the impacts of these increased REE fluxes on environmental ecosystems, whether natural or engineered (e.g., biological waste treatment systems). We have been evaluating the <span class="hlt">effects</span> of europium and yttrium on hydrogen production by an anaerobic fermenting microorganism, Sporacetigenium mesophilum, originally isolated from an anaerobic digester at a wastewater treatment plant.1 Europium and yttrium are important components of phosphors used in fluorescent lighting, and are expected to be recycled in larger quantities in the future. Also tested was the compound tributyl phosphate (TBP), a widely used complexing agent in lanthanide and actinide separations. TBP and related compounds may be used in recycling processes for REE. S. mesophilumcultures were amended with Eu at 100 ppb, 1 ppm and 10 ppm and hydrogen production was measured. While the lowest Eu concentration had minimal <span class="hlt">effect</span> on hydrogen production compared to the no Eu control, the two higher Eu amendment levels appeared to enhance hydrogen production. TBP at 0.1 g/L completely inhibited hydrogen production. Measurements of aqueous Eu concentrations indicated that >85% of the added Eu remained soluble at all three of the Eu addition levels tested. Experiments to ascertain whether enhancement (or inhibition) occurs at even higher Eu concentrations are underway, as are corresponding experiments with yttrium. This work contributes to the assessment of the potential impacts of increased REE recycling and processing on ecosystems, and supports decision making with respect to disposal of wastewaters generated during these industrial practices. 1Chen, S., Song, L. and X. Dong. Int J. Syst. Evol. Microbiol. 56, 721-725, doi: 10.1099/ijs.0.63686-0 (2006).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930001397','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930001397"><span>Space environmental <span class="hlt">effects</span> on LDEF low <span class="hlt">Earth</span> orbit exposed graphite reinforced polymer matrix composites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>George, Pete</p> <p>1992-01-01</p> <p>The Long Duration Exposure Facility (LDEF) was deployed on April 7, 1984 in low <span class="hlt">earth</span> orbit (LEO) at an altitude of 482 kilometers. On board experiments experienced the harsh LEO environment including atomic oxygen (AO), ultraviolet radiation (UV), and thermal cycling. During the 5.8 year mission, the LDEF orbit decayed to 340 kilometers where significantly higher AO concentrations exist. LDEF was retrieved on January 12, 1990 from this orbit. One experiment on board LDEF was M0003, Space <span class="hlt">Effects</span> on Spacecraft Materials. As a subset of M0003 nearly 500 samples of polymer, metal, and glass matrix composites were flown as the Advanced Composites Experiment M0003-10. The Advanced Composites Experiment is a joint effort between government and industry with the Aerospace Corporation serving as the experiment integrator. A portion of the graphite reinforced polymer matrix composites were furnished by the Boeing Defense and Space Group, Seattle, Washington. Test results and discussions for the Boeing portion of M0003-10 are presented. Experiment and specimen location on the LDEF are presented along with a quantitative summary of the pertinent exposure conditions. Matrix materials selected for the test were epoxy, polysulfone, and polyimide. These composite materials were selected due to their suitability for high performance structural capability in spacecraft applications. Graphite reinforced polymer matrix composites offer higher strength to weight ratios along with excellent dimensional stability. The Boeing space exposed and corresponding ground control composite specimens were subjected to post flight mechanical, chemical, and physical testing in order to determine any changes in critical properties and performance characteristics. Among the more significant findings are the erosive <span class="hlt">effect</span> of atomic oxygen on leading edge exposed specimens and microcracking in non-unidirectionally reinforced flight specimens.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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