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Sample records for center-of-mass p-wave fermionic

  1. Novel p-wave superfluids of fermionic polar molecules

    NASA Astrophysics Data System (ADS)

    Fedorov, A. K.; Matveenko, S. I.; Yudson, V. I.; Shlyapnikov, G. V.

    2016-06-01

    Recently suggested subwavelength lattices offer remarkable prospects for the observation of novel superfluids of fermionic polar molecules. It becomes realistic to obtain a topological p-wave superfluid of microwave-dressed polar molecules in 2D lattices at temperatures of the order of tens of nanokelvins, which is promising for topologically protected quantum information processing. Another foreseen novel phase is an interlayer p-wave superfluid of polar molecules in a bilayer geometry.

  2. Novel p-wave superfluids of fermionic polar molecules.

    PubMed

    Fedorov, A K; Matveenko, S I; Yudson, V I; Shlyapnikov, G V

    2016-01-01

    Recently suggested subwavelength lattices offer remarkable prospects for the observation of novel superfluids of fermionic polar molecules. It becomes realistic to obtain a topological p-wave superfluid of microwave-dressed polar molecules in 2D lattices at temperatures of the order of tens of nanokelvins, which is promising for topologically protected quantum information processing. Another foreseen novel phase is an interlayer p-wave superfluid of polar molecules in a bilayer geometry. PMID:27278711

  3. Novel p-wave superfluids of fermionic polar molecules

    PubMed Central

    Fedorov, A. K.; Matveenko, S. I.; Yudson, V. I.; Shlyapnikov, G. V.

    2016-01-01

    Recently suggested subwavelength lattices offer remarkable prospects for the observation of novel superfluids of fermionic polar molecules. It becomes realistic to obtain a topological p-wave superfluid of microwave-dressed polar molecules in 2D lattices at temperatures of the order of tens of nanokelvins, which is promising for topologically protected quantum information processing. Another foreseen novel phase is an interlayer p-wave superfluid of polar molecules in a bilayer geometry. PMID:27278711

  4. Multiple scattering dynamics of fermions at an isolated p-wave resonance

    NASA Astrophysics Data System (ADS)

    Thomas, R.; Roberts, K. O.; Tiesinga, E.; Wade, A. C. J.; Blakie, P. B.; Deb, A. B.; Kjærgaard, N.

    2016-07-01

    The wavefunction for indistinguishable fermions is anti-symmetric under particle exchange, which directly leads to the Pauli exclusion principle, and hence underlies the structure of atoms and the properties of almost all materials. In the dynamics of collisions between two indistinguishable fermions, this requirement strictly prohibits scattering into 90° angles. Here we experimentally investigate the collisions of ultracold clouds fermionic 40K atoms by directly measuring scattering distributions. With increasing collision energy we identify the Wigner threshold for p-wave scattering with its tell-tale dumb-bell shape and no 90° yield. Above this threshold, effects of multiple scattering become manifest as deviations from the underlying binary p-wave shape, adding particles either isotropically or axially. A shape resonance for 40K facilitates the separate observation of these two processes. The isotropically enhanced multiple scattering mode is a generic p-wave threshold phenomenon, whereas the axially enhanced mode should occur in any colliding particle system with an elastic scattering resonance.

  5. Multiple scattering dynamics of fermions at an isolated p-wave resonance.

    PubMed

    Thomas, R; Roberts, K O; Tiesinga, E; Wade, A C J; Blakie, P B; Deb, A B; Kjærgaard, N

    2016-01-01

    The wavefunction for indistinguishable fermions is anti-symmetric under particle exchange, which directly leads to the Pauli exclusion principle, and hence underlies the structure of atoms and the properties of almost all materials. In the dynamics of collisions between two indistinguishable fermions, this requirement strictly prohibits scattering into 90° angles. Here we experimentally investigate the collisions of ultracold clouds fermionic (40)K atoms by directly measuring scattering distributions. With increasing collision energy we identify the Wigner threshold for p-wave scattering with its tell-tale dumb-bell shape and no 90° yield. Above this threshold, effects of multiple scattering become manifest as deviations from the underlying binary p-wave shape, adding particles either isotropically or axially. A shape resonance for (40)K facilitates the separate observation of these two processes. The isotropically enhanced multiple scattering mode is a generic p-wave threshold phenomenon, whereas the axially enhanced mode should occur in any colliding particle system with an elastic scattering resonance. PMID:27396294

  6. One-dimensional fermionic gases with attractive p -wave interaction in a hard-wall trap

    NASA Astrophysics Data System (ADS)

    Hao, Yajiang; Zhang, Yunbo; Chen, Shu

    2007-12-01

    We investigate the ground state of the one-dimensional fermionic system enclosed in a hard-wall trap with attractive contact p -wave interactions. Based on the Bethe ansatz method, the explicit wave function is derived by numerically solving the Bethe ansatz equations for the full physical regimes (-∞≤cF≤0) . With the exact wave function some quantities which are important in many-body physics are obtained, including the one-body density matrix and the momentum distribution of the ground state for finite system. It is shown that the shell structure of the density profiles disappears with the increase of the interaction and in the fermionic Tonks-Girardeau limit the density distribution shows the same behavior as that of an ideal Bose gas. However, the one-body density matrix and the momentum distribution exhibit completely different structures compared with their bosonic counterparts.

  7. Majorana modes and p-wave superfluids for fermionic atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    Bühler, A.; Lang, N.; Kraus, C. V.; Möller, G.; Huber, S. D.; Büchler, H. P.

    2014-07-01

    The quest for realization of non-Abelian phases of matter, driven by their possible use in fault-tolerant topological quantum computing, has been spearheaded by recent developments in p-wave superconductors. The chiral px+ipy-wave superconductor in two-dimensions exhibiting Majorana modes provides the simplest phase supporting non-Abelian quasiparticles and can be seen as the blueprint of fractional topological order. Alternatively, Kitaev’s Majorana wire has emerged as an ideal toy model to understand Majorana modes. Here we present a way to make the transition from Kitaev's Majorana wires to two-dimensional p-wave superconductors in a system with cold atomic gases in an optical lattice. The main idea is based on an approach to generate p-wave interactions by coupling orbital degrees of freedom with strong s-wave interactions. We demonstrate how this design can induce Majorana modes at edge dislocations in the optical lattice, and we provide an experimentally feasible protocol for the observation of the non-Abelian statistics.

  8. Center of Mass Demonstration on the Fly

    ERIC Educational Resources Information Center

    Hazelrigg, Conner; Baker, Blane

    2015-01-01

    Center of mass (CM) is an important concept in physics, especially when studying extended bodies. For example, general motion of an extended body can be considered as the sum of the translational motion of the CM plus other types of motion about that CM. CM also can be regarded as a "balance point" so that a system supported at its CM…

  9. Three Methods of Finding Center of Mass.

    ERIC Educational Resources Information Center

    Reidl, Charles J., Jr.

    1995-01-01

    Presents a procedure that students can use to determine the center of mass of a thin (two-dimensional), homogenous object experimentally, analytically, and numerically. Requires students to use three distinctly different approaches to a single problem and necessitates a combination of laboratory skills, a knowledge of fundamental calculus, and…

  10. Majorana fermions in a topological superconducting wire out of equilibrium: Exact microscopic transport analysis of a p-wave open chain coupled to normal leads

    NASA Astrophysics Data System (ADS)

    Roy, Dibyendu; Bolech, C. J.; Shah, Nayana

    2012-09-01

    Topological superconductors are prime candidates for the implementation of topological-quantum-computation ideas because they can support non-Abelian excitations such as Majorana fermions. We go beyond the low-energy effective-model descriptions of Majorana bound states (MBSs) to derive nonequilibrium transport properties of wire geometries of these systems in the presence of arbitrarily large applied voltages. Our approach involves quantum Langevin equations and nonequilibrium Green's functions. By virtue of a full microscopic calculation we are able to model the tunnel coupling between the superconducting wire and the metallic leads realistically, study the role of high-energy nontopological excitations, predict how the behavior compares for an increasing number of odd versus even number of sites, and study the evolution across the topological quantum phase transition (QPT). We find that the normalized spectral weight in the MBSs can be remarkably large and goes to zero continuously at the topological QPT. Our results have concrete implications for the experimental search and study of MBSs.

  11. Center of mass demonstration on the fly

    NASA Astrophysics Data System (ADS)

    Hazelrigg, Conner; Baker, Blane

    2015-01-01

    Center of mass (CM) is an important concept in physics, especially when studying extended bodies.1 For example, general motion of an extended body can be considered as the sum of the translational motion of the CM plus other types of motion about that CM. CM also can be regarded as a "balance point" so that a system supported at its CM remains in static equilibrium. In the context of Newton's laws of motion, acceleration of CM is determined by the ratio of the net external force acting on a system to the system's total mass. Given the usefulness of CM in analyzing numerous motions, knowing concepts associated with CM is helpful for students of physics. Within the physics community, previous workers have discussed centers of mass of various toys2 and described experiments to determine centers of mass.3,4 Here we describe a quickly assembled demonstration to show static equilibrium of an object when it is supported along a line of action through its CM.

  12. Center of mass detection via an active pixel sensor

    NASA Technical Reports Server (NTRS)

    Yadid-Pecht, Orly (Inventor); Minch, Brad (Inventor); Pain, Bedabrata (Inventor); Fossum, Eric (Inventor)

    2002-01-01

    An imaging system for identifying the location of the center of mass (COM) in an image. In one aspect, an imaging system includes a plurality of photosensitive elements arranged in a matrix. A center of mass circuit coupled to the photosensitive elements includes a resistive network and a normalization circuit including at least one bipolar transistor. The center of mass circuit identifies a center of mass location in the matrix and includes: a row circuit, where the row circuit identifies a center of mass row value in each row of the matrix and identifies a row intensity for each row; a horizontal circuit, where the horizontal circuit identifies a center of mass horizontal value; and a vertical circuit, where the vertical circuit identifies a center of mass vertical value. The horizontal and vertical center of mass values indicate the coordinates of the center of mass location for the image.

  13. Center of mass detection via an active pixel sensor

    NASA Technical Reports Server (NTRS)

    Yadid-Pecht, Orly (Inventor); Minch, Brad (Inventor); Pain, Bedabrata (Inventor); Fossum, Eric (Inventor)

    2005-01-01

    An imaging system for identifying the location of the center of mass (COM) in an image. In one aspect, an imaging system includes a plurality of photosensitive elements arranged in a matrix. A center of mass circuit coupled to the photosensitive elements includes a resistive network and a normalization circuit including at least one bipolar transistor. The center of mass circuit identifies a center of mass location in the matrix and includes: a row circuit, where the row circuit identifies a center of mass row value in each row of the matrix and identifies a row intensity for each row; a horizontal circuit, where the horizontal circuit identifies a center of mass horizontal value; and a vertical circuit, where the vertical circuit identifies a center of mass vertical value. The horizontal and vertical center of mass values indicate the coordinates of the center of mass location for the image.

  14. Center of mass detection via an active pixel sensor

    NASA Technical Reports Server (NTRS)

    Yadid-Pecht, Orly (Inventor); Minch, Brad (Inventor); Pain, Bedabrara (Inventor); Fossum, Eric (Inventor)

    2006-01-01

    An imaging system for identifying the location of the center of mass (COM) in an image. In one aspect, an imaging system includes a plurality of photosensitive elements arranged in a matrix. A center of mass circuit coupled to the photosensitive elements includes a resistive network and a normalization circuit including at least one bipolar transistor. The center of mass circuit identifies a center of mass location in the matrix and includes: a row circuit, where the row circuit identifies a center of mass row value in each row of the matrix and identifies a row intensity for each row; a horizontal circuit, where the horizontal circuit identifies a center of mass horizontal value; and a vertical circuit, where the vertical circuit identifies a center of mass vertical value. The horizontal and vertical center of mass values indicate the coordinates of the center of mass location for the image.

  15. The Center of Mass of a Soft Spring

    ERIC Educational Resources Information Center

    Serna, Juan D.; Joshi, Amitabh

    2011-01-01

    This article uses calculus to find the center of mass of a soft, vertically suspended, cylindrical helical spring, which necessarily is stretched non-uniformly by the action of gravity. A general expression for the vertical position of the center of mass is obtained and compared with other results in the literature.

  16. Where Is the Center of Mass of Florida?

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2007-09-01

    An attention-grabbing center-of-mass demonstration uses the map of a state mounted on a sheet of heavy cardboard and cut out along the boundaries. The two-dimensional object is hung from a hole punched into a city near the edge, and a string with a pendulum bob attached to it passes through the center of mass. The process is repeated with a different city, and the center of mass is determined uniquely. I did this regularly with a map of the state of Ohio, and the geographic center of the state reliably came out to be the nearby village of Centerburg.

  17. Measurement of Chern numbers through center-of-mass responses

    NASA Astrophysics Data System (ADS)

    Price, H. M.; Zilberberg, O.; Ozawa, T.; Carusotto, I.; Goldman, N.

    2016-06-01

    Probing the center-of-mass of an ultracold atomic cloud can be used to measure Chern numbers, the topological invariants underlying the quantum Hall effects. In this work, we show how such center-of-mass observables can have a much richer dependence on topological invariants than previously discussed. In fact, the response of the center of mass depends not only on the current density, typically measured in a solid-state system, but also on the particle density, which itself can be sensitive to the topology of the band structure. We apply a semiclassical approach, supported by numerical simulations, to highlight the key differences between center-of-mass responses and more standard conductivity measurements. We illustrate this by analyzing both the two- and four-dimensional quantum Hall effects. These results have important implications for experiments in engineered topological systems, such as ultracold gases and photonics.

  18. Effective p -wave interaction and topological superfluids in s -wave quantum gases

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Zheng, Zhen; Pu, Han; Zou, Xubo; Guo, Guangcan

    2016-03-01

    p -wave interaction in cold atoms may give rise to exotic topological superfluids. However, the realization of p -wave interaction in a cold atom system is experimentally challenging. Here we propose a simple scheme to synthesize effective p -wave interaction in conventional s -wave interacting quantum gases. The key idea is to load atoms into a spin-dependent optical lattice potential. Using two concrete examples involving spin-1/2 fermions, we show how the original system can be mapped into a model describing spinless fermions with nearest-neighbor p -wave interaction, whose ground state can be a topological superfluid that supports Majorana fermions under proper conditions. Our proposal has the advantage that it does not require spin-orbit coupling or loading atoms onto higher orbitals, which is the key in earlier proposals to synthesize effective p -wave interaction in s -wave quantum gases, and may provide a completely new route for realizing p -wave topological superfluids.

  19. Where Is the Center of Mass of Florida?

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2007-01-01

    An attention-grabbing center-of-mass demonstration uses the map of a state mounted on a sheet of heavy cardboard and cut out along the boundaries. The two-dimensional object is hung from a hole punched into a city near the edge, and a string with a pendulum bob attached to it passes through the center of mass. The process is repeated with a…

  20. Symmetry comparison between sacrum and center of mass during walking.

    PubMed

    Navvab Motlagh, Fateme; Arshi, Ahmed Reza

    2016-07-01

    Sacrum motion is used extensively in clinical research to represent movement of the entire body by replacing the center of mass. The primary objective of this article was to investigate the effect of this replacement on symmetry determination. The secondary objective was to assess the correlation between the symmetries of trajectories of center of mass and sacrum, and that of spatiotemporal parameters. Three-dimensional trajectories obtained from 37 markers placed on anatomical landmarks of 15 healthy subjects were recorded while walking at three speeds on the treadmill. Trajectory of center of mass was determined using segmental analysis method. The results indicated that two symmetries, one determined using sacrum marker and the other using segmental analysis method, were different and this difference was more pronounced in anterior-posterior direction. In other words, harmonic analysis of sacrum and center of mass trajectories revealed different results. Furthermore, low-to-moderate correlations were observed between spatiotemporal parameters symmetry and symmetries obtained from both center of mass and sacrum. In conclusion, the results indicated that it may not be analytically acceptable to substitute sacrum for center of mass in symmetry determination. PMID:27272201

  1. Planning Paths Through Singularities in the Center of Mass Space

    NASA Technical Reports Server (NTRS)

    Doggett, William R.; Messner, William C.; Juang, Jer-Nan

    1998-01-01

    The center of mass space is a convenient space for planning motions that minimize reaction forces at the robot's base or optimize the stability of a mechanism. A unique problem associated with path planning in the center of mass space is the potential existence of multiple center of mass images for a single Cartesian obstacle, since a single center of mass location can correspond to multiple robot joint configurations. The existence of multiple images results in a need to either maintain multiple center of mass obstacle maps or to update obstacle locations when the robot passes through a singularity, such as when it moves from an elbow-up to an elbow-down configuration. To illustrate the concepts presented in this paper, a path is planned for an example task requiring motion through multiple center of mass space maps. The object of the path planning algorithm is to locate the bang- bang acceleration profile that minimizes the robot's base reactions in the presence of a single Cartesian obstacle. To simplify the presentation, only non-redundant robots are considered and joint non-linearities are neglected.

  2. Holographic p -wave superfluid

    NASA Astrophysics Data System (ADS)

    Wu, Ya-Bo; Lu, Jun-Wang; Zhang, Wen-Xin; Zhang, Cheng-Yuan; Lu, Jian-Bo; Yu, Fang

    2014-12-01

    In the probe limit, we numerically construct a holographic p -wave superfluid model in the four-dimensional (4D) and five-dimensional (5D) anti-de Sitter black holes coupled to a Maxwell-complex vector field. We find that, for the condensate with the fixed superfluid velocity, the results are similar to the s -wave cases in both 4D and 5D spacetimes. In particular, the Cave of Winds and the phase transition, always being of second order, take place in the 5D case. Moreover, we find that the translating superfluid velocity from second order to first order S/yμ increases with the mass squared. Furthermore, for the supercurrent with fixed temperature, the results agree with the Ginzburg-Landau prediction near the critical temperature. In addition, this complex vector superfluid model is still a generalization of the SU(2) superfluid model, and it also provides a holographic realization of the H e3 superfluid system.

  3. Cavity QED with Quantized Center of Mass Motion

    NASA Astrophysics Data System (ADS)

    Leach, Joe; Rice, P. R.

    2004-09-01

    We investigate the quantum fluctuations of a single atom in a weakly driven cavity, where the center of mass motion of the atom is quantized in one dimension. We present analytic results for the second order intensity correlation function g(2)(τ) and the intensity-field correlation function hθ(τ), for transmitted light in the weak driving field limit. We find that the coupling of the center of mass motion to the intracavity field mode can be deleterious to nonclassical effects in photon statistics and field-intensity correlations, and compare the use of trapped atoms in a cavity to atomic beams.

  4. Accurate measurements of mass and center of mass

    NASA Technical Reports Server (NTRS)

    Chow, E. Y.; Trubert, M. R.

    1979-01-01

    Object is measured for mass and center of mass with accuracies of 0.01% and 0.14 respectively, using method that eliminates errors in alignment, leveling, and calibration. Method is applied to scientific instruments, recorder turntables, flywheels, and other devices that require precise balancing.

  5. Synthetic p-wave interaction and topological superfluids in s-wave quantum gases

    NASA Astrophysics Data System (ADS)

    Pu, Han; Wang, Bin; Zheng, Zhen; Zou, Xubo; Guo, Guangcan

    2016-05-01

    P-wave interaction in cold atoms may give rise to exotic topological superfluids. However, realization of p-wave interaction in cold atom system is experimentally challenging. Here we propose a simple scheme to synthesize effective p-wave interaction in conventional s-wave interacting quantum gases. The key idea is to load atoms into spin-dependent optical lattice potential. Using two concrete examples involving spin-1/2 fermions, we show how the original system can be mapped into a model describing spinless fermions with nearest neighbor p-wave interaction, whose ground state can be a topological superfluid that supports Majorana fermions under proper conditions. Our proposal has the advantage that it does not require spin-orbit coupling or loading atoms onto higher orbitals, which is the key in earlier proposals to synthesize effective p-wave interaction in s-wave quantum gases, and may provide a completely new route for realizing p-wave topological superfluids.

  6. Venus' center of mass - center of figure displacement and implications

    NASA Technical Reports Server (NTRS)

    Bindschadler, D. L.; Schubert, G.

    1993-01-01

    Earth, Moon, Mars, and Venus all have centers of mass (C.M.) that are displaced from their centers of figure (C.F.) by amounts which range from 340 meters (Venus) to 2.5 km (Mars). These offsets have all been calculated from the first degree terms in spherical harmonic expansions of topography. We describe an alternate method for calculating C.M. - C.F. offsets directly from a global topographic data set and apply it to Venus. Using Magellan altimetry, we find that Venus' C.F. is displaced approximately 280 meters from its C.M. in the direction of Western Aphrodite Terra (4.4 deg S, 135.8 deg E). We investigate several simple models for this offset and find that it is most consistent with thickened crust in Ovda and Thetis Regiones (which constitute most of W. Aphrodite). The location of the C.F. offset also places constraints on the degree of crustal thickening in Western Ishtar Terra and/or this highland's mode of origin. We favor a model in which offset due to thick crust in Western Ishtar Terra is balanced by an opposing offset due to cold, downwelling mantle material beneath the highland.

  7. Impacts of Center of Mass Shifts on Messenger Spacecraft Operations

    NASA Technical Reports Server (NTRS)

    O'Shaughnessy, D. J.; Vaughan, R. M.; Chouinard, T. L., III; Jaekle, D. E.

    2007-01-01

    The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) has successfully completed its first three years of flight operations following launch on August 3, 2004. As part of NASA s Discovery Program, MESSENGER will observe Mercury during flybys in 2008 and 2009, as well as from orbit beginning in March 2011. This paper discusses the impact that center of mass (CM) location changes have had on many mission activities, particularly angular momentum management and maneuver execution. Momentum trends were altered significantly following the first deep-space maneuver, and these changes were related to a change in the CM. The CM location also impacts maneuver execution, and uncertainties in its location led to the significant direction errors experienced at trajectory correction maneuver 11. Because of the spacecraft sensitivity to CM location, efforts to estimate its position are important to momentum and maneuver prediction. This paper summarizes efforts to estimate the CM from flight data, as well as the operational strategy to handle CM uncertainties and their impact on momentum trends and maneuver execution accuracy.

  8. Anisotropic Fermi Superfluid via p-Wave Feshbach Resonance

    SciTech Connect

    Cheng, C.-H.; Yip, S.-K.

    2005-08-12

    We investigate theoretically fermionic superfluidity induced by Feshbach resonance in the orbital p-wave channel and determine the general phase diagram. In contrast with superfluid {sup 3}He, due to the dipole interaction, the pairing is extremely anisotropic. When this dipole interaction is relatively strong, the pairing has symmetry k{sub z}. When it is relatively weak, it is of symmetry k{sub z}+i{beta}k{sub y} (up to a rotation about k{sub z}, here {beta}<1). A phase transition between these two states can occur under a change in the magnetic field or the density of the gas.

  9. p-Wave Cold Collisions in an Optical Lattice Clock

    SciTech Connect

    Lemke, N. D.; Sherman, J. A.; Oates, C. W.; Ludlow, A. D.; Stecher, J. von; Rey, A. M.

    2011-09-02

    We study ultracold collisions in fermionic ytterbium by precisely measuring the energy shifts they impart on the atoms' internal clock states. Exploiting Fermi statistics, we uncover p-wave collisions, in both weakly and strongly interacting regimes. With the higher density afforded by two-dimensional lattice confinement, we demonstrate that strong interactions can lead to a novel suppression of this collision shift. In addition to reducing the systematic errors of lattice clocks, this work has application to quantum information and quantum simulation with alkaline-earth atoms.

  10. Venus' center of figure-center of mass offset

    NASA Technical Reports Server (NTRS)

    Bindschadler, Duane L.; Schubert, Gerald; Ford, Peter G.

    1994-01-01

    Magellan altimetry data reveal that the center of figure (CF) of Venus is displaced approximately 280 m from its center of mass (CM) toward 4.4 deg S, 135.8 deg E, a location in Aphrodite Terra. This offset is smaller than those of other terrestrial planets but larger than the estimated error, which is no more than a few tens of meters. We examine the possibility that the CF-CM offset is related to specific geologic provinces on Venus by deriving three simple models for the offset: a thick-crust model, a hotspot model, and a thick-lithosphere model. The offset caused by a region of thick crust depends upon the region's extent, the crust-mantle density contrast, and the thickness of excess crust. A hotspot-related offset depends on the extent of the thermally anomalous region and the magnitude of the thermal anomaly. Offset due to a region of thick lithosphere depends upon the extent of the region, the average temperature contrast across the lithosphere, and the amount of excess lithosphere. We apply the three models to Venus plateau-shaped highlands, volcanic rises, and lowlands, respectively, in an attempt to match the observed CF-CM offset location and magnitude. The influence of most volcanic rises and of Ishtar Terra on the CF-CM offset must be quite small if we are to explain the direction of the observed offset. The lack of influence of volcanic rises can be explained if the related thermal anomalies are limited to a few hundred degrees or less and are plume-shaped (i.e., characterized by a flattened sublithospheric `head' with a narrow cylindrical feeder `tail'). The unimportance of Ishtar Terra is most easily explained if it lies atop a significant mantle downwelling.

  11. Center of mass mechanics of chimpanzee bipedal walking.

    PubMed

    Demes, Brigitte; Thompson, Nathan E; O'Neill, Matthew C; Umberger, Brian R

    2015-03-01

    Center of mass (CoM) oscillations were documented for 81 bipedal walking strides of three chimpanzees. Full-stride ground reaction forces were recorded as well as kinematic data to synchronize force to gait events and to determine speed. Despite being a bent-hip, bent-knee (BHBK) gait, chimpanzee walking uses pendulum-like motion with vertical oscillations of the CoM that are similar in pattern and relative magnitude to those of humans. Maximum height is achieved during single support and minimum height during double support. The mediolateral oscillations of the CoM are more pronounced relative to stature than in human walking when compared at the same Froude speed. Despite the pendular nature of chimpanzee bipedalism, energy recoveries from exchanges of kinetic and potential energies are low on average and highly variable. This variability is probably related to the poor phasic coordination of energy fluctuations in these facultatively bipedal animals. The work on the CoM per unit mass and distance (mechanical cost of transport) is higher than that in humans, but lower than that in bipedally walking monkeys and gibbons. The pronounced side sway is not passive, but constitutes 10% of the total work of lifting and accelerating the CoM. CoM oscillations of bipedally walking chimpanzees are distinctly different from those of BHBK gait of humans with a flat trajectory, but this is often described as "chimpanzee-like" walking. Human BHBK gait is a poor model for chimpanzee bipedal walking and offers limited insights for reconstructing early hominin gait evolution. PMID:25407636

  12. P-wave Variability and Atrial Fibrillation

    PubMed Central

    Censi, Federica; Corazza, Ivan; Reggiani, Elisa; Calcagnini, Giovanni; Mattei, Eugenio; Triventi, Michele; Boriani, Giuseppe

    2016-01-01

    The analysis of P-wave template has been widely used to extract indices of Atrial Fibrillation (AF) risk stratification. The aim of this paper was to assess the potential of the analysis of the P-wave variability over time in patients suffering from atrial fibrillation. P-wave features extracted from P-wave template together with novel indices of P-wave variability have been estimated in a population of patients suffering from persistent AF and compared to those extracted from control subjects. We quantify the P-wave variability over time using three algorithms and we extracted three novel indices: one based on the cross-correlation coefficients among the P-waves (Cross-Correlation Index, CCI), one associated to variation in amplitude of the P-waves (Amplitude Dispersion Index, ADI), one sensible to the phase shift among P-waves (Warping Index, WI). The control group resulted to be characterized by shorter P-wave duration and by a less amount of fragmentation and variability, respect to AF patients. The parameter CCI shows the highest sensitivity (97.3%) and a good specificity (95%). PMID:27225709

  13. The Perception of Limb Orientation Depends on the Center of Mass

    ERIC Educational Resources Information Center

    van de Langenberg, Rolf; Kingma, Idsart; Beek, Peter J.

    2008-01-01

    Three experiments were conducted to test the hypothesis that the perception of limb orientation depends on inertial eigenvectors against the alternative that it depends on the center of mass. In all experiments, each participant pointed at visible targets with his or her occluded right arm while center-of-mass and inertial eigenvectors were…

  14. Development of Visual Center of Mass Localization for Grasp Point Selection

    ERIC Educational Resources Information Center

    Duemmler, Thomas; Schoeberl, Petra; Schwarzer, Gudrun

    2008-01-01

    Adults assess precisely the center of mass (CM) of single-bodied objects and choose grasping points that span an axis through or close to the center of mass when lifting them. The present study examined how children and adults assess the CM when lifting two-bodied objects (barbells) and how this ability develops. Four- to five-year olds, 6- to…

  15. p-wave optical Feshbach resonances in {sup 171}Yb

    SciTech Connect

    Goyal, Krittika; Deutsch, Ivan; Reichenbach, Iris

    2010-12-15

    We study the use of an optical Feshbach resonance to modify the p-wave interaction between ultracold polarized {sup 171}Yb spin-1/2 fermions. A laser exciting two colliding atoms to the {sup 1}S{sub 0}+{sup 3}P{sub 1} channel can be detuned near a purely-long-range excited molecular bound state. Such an exotic molecule has an inner turning point far from the chemical binding region, and thus, three-body recombination in the Feshbach resonance will be highly suppressed in contrast to that typically seen in a ground-state p-wave magnetic Feshbach resonance. We calculate the excited molecular bound-state spectrum using a multichannel integration of the Schroedinger equation, including an external perturbation by a magnetic field. From the multichannel wave functions, we calculate the Feshbach resonance properties, including the modification of the elastic p-wave scattering volume and inelastic spontaneous scattering rate. The use of magnetic fields and selection rules for polarized light yields a highly controllable system. We apply this control to propose a toy model for three-color superfluidity in an optical lattice for spin-polarized {sup 171}Yb, where the three colors correspond to the three spatial orbitals of the first excited p band. We calculate the conditions under which tunneling and on-site interactions are comparable, at which point quantum critical behavior is possible.

  16. Engineering quantum magnetism in one-dimensional trapped Fermi gases with p -wave interactions

    NASA Astrophysics Data System (ADS)

    Yang, Lijun; Guan, Xiwen; Cui, Xiaoling

    2016-05-01

    The highly controllable ultracold atoms in a one-dimensional (1D) trap provide a new platform for the ultimate simulation of quantum magnetism. In this regard, the Néel antiferromagnetism and the itinerant ferromagnetism are of central importance and great interest. Here we show that these magnetic orders can be achieved in the strongly interacting spin-1/2 trapped Fermi gases with additional p -wave interactions. In this strong-coupling limit, the 1D trapped Fermi gas exhibits an effective Heisenberg spin X X Z chain in the anisotropic p -wave scattering channels. For a particular p -wave attraction or repulsion within the same species of fermionic atoms, the system displays ferromagnetic domains with full spin segregation or the antiferromagnetic spin configuration in the ground state. Such engineered magnetisms are likely to be probed in a quasi-1D trapped Fermi gas of 40K atoms with very close s -wave and p -wave Feshbach resonances.

  17. Chiral superfluidity with p-wave symmetry from an interacting s-wave atomic Fermi gas.

    PubMed

    Liu, Bo; Li, Xiaopeng; Wu, Biao; Liu, W Vincent

    2014-01-01

    Chiral p-wave superfluids are fascinating topological quantum states of matter that have been found in the liquid (3)He-A phase and arguably in the electronic Sr2RuO4 superconductor. They are fundamentally related to the fractional 5/2 quantum Hall state, which supports fractional exotic excitations. Past studies show that they require spin-triplet pairing of fermions by p-wave interaction. Here we report that a p-wave chiral superfluid state can arise from spin-singlet pairing for an s-wave interacting atomic Fermi gas in an optical lattice. This p-wave state is conceptually distinct from all previous conventional p-wave states as it is for the centre-of-mass motion, instead of the relative motion. It leads to spontaneous generation of angular momentum, finite Chern numbers and topologically protected chiral fermionic zero modes bounded to domain walls, all occuring at a higher critical temperature in relative scales. Signature quantities are predicted for the cold atom experimental condition. PMID:25266996

  18. CALCOM: A software for calculating the center of mass of proteins

    PubMed Central

    Costantini, Susan; Paladino, Antonella; Facchiano, Angelo M

    2008-01-01

    The center of mass of a protein is an artificial point useful for detecting important and simple features of proteins structure, shape and association. CALCOM is a software which calculates the center of mass of a protein, starting from PDB protein structure files. In the case of protein complexes and of protein-small ligand complexes, the position of protein residues or of ligand atoms respect to each protein subunit can be evaluated, as well as the distance among the center of mass of the protein subunits, in order to compare different conformations and evaluate the relative motion of subunits. Availability The service is available at the URL: http://bioinformatica.isa.cnr.it/CALCOM/. PMID:18478078

  19. Center-of-mass energy for the Plebanski-Demianski black hole

    SciTech Connect

    Sharif, M. Haider, Nida

    2013-07-15

    We study the center-of-mass energy of the particles colliding in the vicinity of acceleration and event horizons of the Plebanski and Demianski class of black holes. We calculate the collision energy of uncharged particles in the center-of-mass frame that are freely falling along the equatorial plane of a charged accelerating and rotating black hole with an NUT parameter. This energy turns out to be infinite in the non-extremal case, while in the extremal case, it becomes infinitely large near the event horizon only if the particle has the critical angular momentum. We conclude that the center-of-mass energy depends on the rotation and the NUT parameter.

  20. Minimizing center of mass vertical movement increases metabolic cost in walking.

    PubMed

    Ortega, Justus D; Farley, Claire T

    2005-12-01

    A human walker vaults up and over each stance limb like an inverted pendulum. This similarity suggests that the vertical motion of a walker's center of mass reduces metabolic cost by providing a mechanism for pendulum-like mechanical energy exchange. Alternatively, some researchers have hypothesized that minimizing vertical movements of the center of mass during walking minimizes the metabolic cost, and this view remains prevalent in clinical gait analysis. We examined the relationship between vertical movement and metabolic cost by having human subjects walk normally and with minimal center of mass vertical movement ("flat-trajectory walking"). In flat-trajectory walking, subjects reduced center of mass vertical displacement by an average of 69% (P = 0.0001) but consumed approximately twice as much metabolic energy over a range of speeds (0.7-1.8 m/s) (P = 0.0001). In flat-trajectory walking, passive pendulum-like mechanical energy exchange provided only a small portion of the energy required to accelerate the center of mass because gravitational potential energy fluctuated minimally. Thus, despite the smaller vertical movements in flat-trajectory walking, the net external mechanical work needed to move the center of mass was similar in both types of walking (P = 0.73). Subjects walked with more flexed stance limbs in flat-trajectory walking (P < 0.001), and the resultant increase in stance limb force generation likely helped cause the doubling in metabolic cost compared with normal walking. Regardless of the cause, these findings clearly demonstrate that human walkers consume substantially more metabolic energy when they minimize vertical motion. PMID:16051716

  1. Quantum fluctuations in a cavity-QED system with quantized center-of-mass motion

    NASA Astrophysics Data System (ADS)

    Leach, J. R.; Mumba, M.; Rice, P. R.

    2011-06-01

    We investigate the quantum fluctuations of a single atom in a weakly driven cavity where the center-of-mass motion of the atom is quantized in one dimension. We present analytic results for the second-order intensity correlation function g(2)(τ) and the intensity-field correlation function hθ(τ) for both transmitted and fluorescent light for weak driving fields. We find that the coupling of the center-of-mass motion to the intracavity field mode can be deleterious to nonclassical effects in photon statistics, but less so for the intensity-field correlations.

  2. The effect of center-of-mass motion on photon statistics

    SciTech Connect

    Zhang, Yang; Zhang, Jun; Wu, Shao-xiong; Yu, Chang-shui

    2015-10-15

    We analyze the photon statistics of a weakly driven cavity quantum electrodynamics system and discuss the effects of photon blockade and photon-induced tunneling by effectively utilizing instead of avoiding the center-of-mass motion of a two-level atom trapped in the cavity. With the resonant interaction between atom, photon and phonon, it is shown that the bunching and anti-bunching of photons can occur with properly driving frequency. Our study shows the influence of the imperfect cooling of atom on the blockade and provides an attempt to take advantage of the center-of-mass motion.

  3. Center of mass estimation in closed vortices - A verification in principle and practice

    NASA Technical Reports Server (NTRS)

    Hooker, S. B.; Olson, D. B.

    1984-01-01

    The problem of tracking closed mesoscale vortices using center of mass estimation techniques is studied. Three estimators are evaluated using data from a warm core Gulf Stream ring. The comparisons show that a method based on the intersection of perpendicular bisectors and one using a least-squares fit of a conic section perform comparably. The perpendicular bisector algorithm is used in conjunction with a Gaussian ring model and a star-shaped survey pattern to produce an expected error curve as a function of vortex translation, survey speed and vortex size. For typical ring parameters, center estimation is usually possible to within + or - 5 km. The feasibility of using differing data sets to construct a history of ring motion based on a coordinate system moving with the ring is also investigated. In this way, the validity of using satellite-derived data and drifter trajectories to estimate the center of mass of a mesoscale feature is assessed. The results of the analysis demonstrate that the location of the deeper structure of the ring and the surface expression are sufficiently well correlated to permit dynamically relevant calculations based on surface measurements. It is shown that satellite-derived data can be used to approximate the center of mass trajectory to within the error in the individual center estimates for the period analyzed. The Lagrangian-drifter-derived centers are offset from the center of mass trajectory in a manner consistent with kinematic arguments.

  4. ETALON-1,-2 center of mass correction and array reflectivity

    NASA Technical Reports Server (NTRS)

    Mironov, N. T.; Emetz, A. I.; Zaharov, A. N.; Tchebotarev, V. E.

    1993-01-01

    Center of mass correction to be applied to measured ranges to the ETALON 1 and 2 satellites is considered. Numerical values of the correction and reflectivity from the retroreflector array are computed. The variations of these values with satellite orientation are investigated.

  5. What Do Students Perceive during a Lesson on Center-of-Mass?

    ERIC Educational Resources Information Center

    Liby, Bruce W.; Friedenberg, Jay; Yancopoulos, Sophia

    2009-01-01

    This paper presents an assessment of how students perceive a typical classroom representation of center-of-mass. Participants were shown figures consisting of two filled black circles; they were told that these figures represented spheres or balls. They were then asked to indicate with a mark the point where the spheres would balance, i. e., they…

  6. Kinematics of the Hip and Body Center of Mass in Front Crawl

    PubMed Central

    Fernandes, Ricardo J.; Ribeiro, João; Figueiredo, Pedro; Seifert, Ludovic; Vilas-Boas, João Paulo

    2012-01-01

    The kinematic profiles of the hip and center of mass in front crawl swimming were compared to quantify the error of using a fixed body point to assess intracyclic velocity variations at moderate intensity exercise. The practical goal was to provide a useful tool, easy and fast to assess, and to use as feedback, for assessing swimming efficiency. Sixteen swimmers performed an intermittent incremental protocol that allowed assessing the individual anaerobic threshold velocity. One complete stroke cycle was analysed at the step intensity corresponding to each swimmer’s anaerobic threshold. The subjects were videotaped in the sagittal plane using a double camera set-up for two-dimensional kinematical analyses. The hip and the center of mass presented similar mean velocity and displacement values, being highly related to both parameters. However, the hip reflects the center of mass forward velocity and horizontal displacement with 7.54% and 3.24% associated error, respectively. Differences between hip and center of mass were observed for intracyclic velocity variations (0.19±0.05 and 0.25±0.08, respectively, for a p<0.001), and the negative mean error value found (−0.06) evidenced a tendency of the hip to overestimate the center of mass velocity variation. It is possible to conclude that the hips forward movements might provide a good estimate of the swimmer’s horizontal velocity and displacement that is relevant for diagnostic purposes, especially to assess swimming efficiency through the intracyclic velocity variations. Nevertheless, the hip point error magnitude should be taken into consideration in data interpretation. PMID:23486784

  7. Damping of electron center-of-mass oscillation in ultracold plasmas

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Ting; Witte, Craig; Roberts, Jacob L.

    2016-05-01

    Applying a short electric field pulse to an ultracold plasma induces an electron plasma oscillation. This manifests itself as an oscillation of the electron center of mass around the ion center of mass in the ultracold plasma. In general, the oscillation can damp due to either collisionless or collisional mechanisms, or a combination of the both. To investigate the nature of oscillation damping in ultracold plasmas, we developed a molecular dynamics model of the ultracold plasma electrons. Through this model, we found that depending on the neutrality of the ultracold plasma and the size of an applied DC electric field, there are some parameter ranges where the damping is primarily collisional and some primarily collisionless. We conducted experiments to compare the measured damping rate with theory predictions and found them to be in good agreement. Extension of our measurements to different parameter ranges should enable studies for strong-coupling influence on electron-ion collision rates.

  8. STUDIES FOR MUON COLLIDERS AT CENTER-OF-MASS ENERGIES OF 10 TEV AND 100 TEV.

    SciTech Connect

    KING,B.J.

    1999-03-29

    Parameter lists are presented for speculative muon colliders at center-of-mass energies of 10 TeV and 100 TeV. The technological advances required to achieve the given parameters are itemized and discussed. and a discussion is given of the design goals and constraints. An important constraint for multi-TeV muon colliders is the need to minimize neutrino radiation from the collider ring.

  9. Predicting Dynamic Postural Instability Using Center of Mass Time-to-Contact Information

    PubMed Central

    Hasson, Christopher J.; Van Emmerik, Richard E.A.; Caldwell, Graham E.

    2008-01-01

    Our purpose was to determine whether spatiotemporal measures of center of mass motion relative to the base of support boundary could predict stepping strategies after upper-body postural perturbations in humans. We expected that inclusion of center of mass acceleration in such time-to-contact (TtC) calculations would give better predictions and more advanced warning of perturbation severity. TtC measures were compared with traditional postural variables, which don’t consider support boundaries, and with an inverted pendulum model of dynamic stability developed by Hof et al. (2005). A pendulum was used to deliver sequentially increasing perturbations to 10 young adults, who were strapped to a wooden backboard that constrained motion to sagittal plane rotation about the ankle joint. Subjects were instructed to resist the perturbations, stepping only if necessary to prevent a fall. Peak center of mass and center of pressure velocity and acceleration demonstrated linear increases with postural challenge. In contrast, boundary relevant minimum TtC values decreased nonlinearly with postural challenge, enabling prediction of stepping responses using quadratic equations. When TtC calculations incorporated center of mass acceleration, the quadratic fits were better and gave more accurate predictions of the TtC values that would trigger stepping responses. In addition, TtC minima occurred earlier with acceleration inclusion, giving more advanced warning of perturbation severity. Our results were in agreement with TtC predictions based on Hof’s model, and suggest that TtC may function as a control parameter, influencing the postural control system’s decision to transition from a stationary base of support to a stepping strategy. PMID:18556003

  10. Impact of Center-of-Mass Acceleration on the Performance of Ultramarathon Runners.

    PubMed

    Lin, Shun-Ping; Sung, Wen-Hsu; Kuo, Fon-Chu; Kuo, Terry B J; Chen, Jin-Jong

    2014-12-01

    Ultramarathon races are rapidly gaining popularity in several countries, raising interest for the improvement of training programs. The aim of this study was to use a triaxial accelerometer to compare the three-dimensional center-of-mass accelerations of two groups of ultramarathon runners with distinct performances during different running speeds and distances. Ten runners who participated in the 12-h Taipei International Ultramarathon Race underwent laboratory treadmill testing one month later. They were divided into an elite group (EG; n = 5) and a sub-elite group (SG; n = 5). The triaxial center-of-mass acceleration recorded during a level-surface progressive intensity running protocol (3, 6, 8, 9, 10, and 12 km/h; 5 min each) was used for correlation analyses with running distance during the ultramarathon. The EG showed negative correlations between mediolateral (ML) acceleration (r = -0.83 to -0.93, p < 0.05), and between anterior-posterior (AP) acceleration and running distance (r = -0.8953 to -0.9653, p < 0.05), but not for vertical control of the center of mass. This study suggests that runners reduce stride length to minimize mediolateral sway and the effects of braking on the trunk; moreover, cadence must be increased to reduce braking effects and enhance impetus. Consequently, the competition level of ultramarathons can be elevated. PMID:25713664

  11. Impact of Center-of-Mass Acceleration on the Performance of Ultramarathon Runners

    PubMed Central

    Lin, Shun-Ping; Sung, Wen-Hsu; Kuo, Fon-Chu; Kuo, Terry B.J.; Chen, Jin-Jong

    2014-01-01

    Ultramarathon races are rapidly gaining popularity in several countries, raising interest for the improvement of training programs. The aim of this study was to use a triaxial accelerometer to compare the three-dimensional center-of-mass accelerations of two groups of ultramarathon runners with distinct performances during different running speeds and distances. Ten runners who participated in the 12-h Taipei International Ultramarathon Race underwent laboratory treadmill testing one month later. They were divided into an elite group (EG; n = 5) and a sub-elite group (SG; n = 5). The triaxial center-of-mass acceleration recorded during a level-surface progressive intensity running protocol (3, 6, 8, 9, 10, and 12 km/h; 5 min each) was used for correlation analyses with running distance during the ultramarathon. The EG showed negative correlations between mediolateral (ML) acceleration (r = −0.83 to −0.93, p < 0.05), and between anterior–posterior (AP) acceleration and running distance (r = −0.8953 to −0.9653, p < 0.05), but not for vertical control of the center of mass. This study suggests that runners reduce stride length to minimize mediolateral sway and the effects of braking on the trunk; moreover, cadence must be increased to reduce braking effects and enhance impetus. Consequently, the competition level of ultramarathons can be elevated. PMID:25713664

  12. A highly accurate method for the determination of mass and center of mass of a spacecraft

    NASA Technical Reports Server (NTRS)

    Chow, E. Y.; Trubert, M. R.; Egwuatu, A.

    1978-01-01

    An extremely accurate method for the measurement of mass and the lateral center of mass of a spacecraft has been developed. The method was needed for the Voyager spacecraft mission requirement which limited the uncertainty in the knowledge of lateral center of mass of the spacecraft system weighing 750 kg to be less than 1.0 mm (0.04 in.). The method consists of using three load cells symmetrically located at 120 deg apart on a turntable with respect to the vertical axis of the spacecraft and making six measurements for each load cell. These six measurements are taken by cyclic rotations of the load cell turntable and of the spacecraft, about the vertical axis of the measurement fixture. This method eliminates all alignment, leveling, and load cell calibration errors for the lateral center of mass determination, and permits a statistical best fit of the measurement data. An associated data reduction computer program called MASCM has been written to implement this method and has been used for the Voyager spacecraft.

  13. Fluctuation-dissipation relations for motions of center of mass in driven granular fluids under gravity.

    PubMed

    Wakou, Jun'ichi; Isobe, Masaharu

    2012-06-01

    We investigated the validity of fluctuation-dissipation relations in the nonequilibrium stationary state of fluidized granular media under gravity by two independent approaches, based on theory and numerical simulations. A phenomenological Langevin-type theory describing the fluctuation of center of mass height, which was originally constructed for a one-dimensional granular gas on a vibrating bottom plate, was generalized to any dimensionality, even for the case in which the vibrating bottom plate is replaced by a thermal wall. The theory predicts a fluctuation-dissipation relation known to be satisfied at equilibrium, with a modification that replaces the equilibrium temperature by an effective temperature defined by the center of mass kinetic energy. To test the validity of the fluctuation-dissipation relation, we performed extensive and accurate event-driven molecular dynamics simulations for the model system with a thermal wall at the bottom. The power spectrum and response function of the center of mass height were measured and closely compared with theoretical predictions. It is shown that the fluctuation-dissipation relation for the granular system is satisfied, especially in the high-frequency (short time) region, for a wide range of system parameters. Finally, we describe the relationship between systematic deviations in the low-frequency (long time) region and the time scales of the driven granular system. PMID:23005089

  14. Relativistic effects in the double S- and P-wave charmonium production in e{sup +}e{sup -} annihilation

    SciTech Connect

    Elekina, E. N.; Martynenko, A. P.

    2010-03-01

    On the basis of perturbative QCD and the relativistic quark model we calculate relativistic and bound state corrections in the pair production of S-wave and P-wave charmonium states. Relativistic factors in the production amplitude connected with the relative motion of heavy quarks and the transformation law of the bound state wave function to the reference frame of the moving S- and P-wave mesons are taken into account. For the gluon and quark propagators entering the production vertex function we use a truncated expansion in the ratio of the relative quark momenta to the center-of-mass energy {radical}(s) up to the second order. The relativistic treatment of the wave functions makes all such second order terms convergent, thus allowing the reliable calculation of their contributions to the production cross section. Relativistic corrections to the quark bound state wave functions in the rest frame are considered by means of the QCD generalization of the standard Breit potential. It turns out that the examined effects change essentially the nonrelativistic results of the cross section for the reaction e{sup +}+e{sup -{yields}}J/{Psi}({eta}{sub c})+{chi}{sub cJ}(h{sub c}) at the center-of-mass energy {radical}(s)=10.6 GeV.

  15. Simulated Obstructive Sleep Apnea Increases P-Wave Duration and P-Wave Dispersion

    PubMed Central

    Wons, Annette M.; Rossi, Valentina; Bratton, Daniel J.; Schlatzer, Christian; Schwarz, Esther I.; Camen, Giovanni; Kohler, Malcolm

    2016-01-01

    Background A high P-wave duration and dispersion (Pd) have been reported to be a prognostic factor for the occurrence of paroxysmal atrial fibrillation (PAF), a condition linked to obstructive sleep apnea (OSA). We tested the hypothesis of whether a short-term increase of P-wave duration and Pd can be induced by respiratory manoeuvres simulating OSA in healthy subjects and in patients with PAF. Methods 12-lead-electrocardiography (ECG) was recorded continuously in 24 healthy subjects and 33 patients with PAF, while simulating obstructive apnea (Mueller manoeuvre, MM), obstructive hypopnea (inspiration through a threshold load, ITH), central apnea (AP), and during normal breathing (BL) in randomized order. The P-wave duration and Pd was calculated by using dedicated software for ECG-analysis. Results P-wave duration and Pd significantly increased during MM and ITH compared to BL in all subjects (+13.1ms and +13.8ms during MM; +11.7ms and +12.9ms during ITH; p<0.001 for all comparisons). In MM, the increase was larger in healthy subjects when compared to patients with PAF (p<0.05). Conclusion Intrathoracic pressure swings through simulated obstructive sleep apnea increase P-wave duration and Pd in healthy subjects and in patients with PAF. Our findings imply that intrathoracic pressure swings prolong the intra-atrial and inter-atrial conduction time and therefore may represent an independent trigger factor for the development for PAF. PMID:27071039

  16. Observability of Multiply Reflected P Waves

    NASA Astrophysics Data System (ADS)

    Foundotos, Michel; Nolet, Guust

    2010-05-01

    In order to constrain the shallow structure of the Earth in global tomography, Love and Rayleigh waves are often used. However these waves are mostly sensitive to the S wave velocity structure. P-wave energy is either evanescent, or leaking away at every surface reflection that generates an S wave which travels much deeper into the mantle. For that reason, to study the shallow P velocity structure of the Earth, we need to study P-waves at regional distances if a good seismic station coverage is available. Otherwise we can use multiple P reflections at teleseismic distance when regional data are not available (as in the oceans for instance). The major aim of this work was first of all to ensure that these multiply reflected P waves can adequately be observed in real data and also to investigate how many reflections at the surface these reflected waves can still be seen and to investigate how strongly the amplitude of multiply reflected P diminishes because of energy loss into S waves. For this study we are comparing the synthetic predictions computed with a Spectral Element Method for a spherically symmetric earth (Nissen-Meyer et al, 2007) with observed data. Attention will be made on Synthetics with and without oceanic reflection points and compare these with observations. We used 300 events recorded (90000 seismograms) from the dense network of US ARRAY, which allows us to make a very large number of observations. Our study shows that three times reflected PPP waves are very well observed for epicentral distances > 60 degrees and for events with Mw > 5.5 , despite the ray-theoretical prediction that at certain distances almost all of their compressional energy is converted to shear waves. However, the four times reflected PPPP waves do not appear everywhere clearly. PPPP can be observed for epicentral distances > 90 degrees.

  17. P-Wave Electron-Hydrogen Scattering

    NASA Technical Reports Server (NTRS)

    Bhtia, Anand

    2012-01-01

    A variational wave function incorporating short range correlations via Hylleraas type functions plus long-range polarization terms of the polarized orbital type but with smooth cut-off factors has been used to calculate P-wave phase shifts for electron-hydrogen scattering. This approach gives the direct r(exp -4) potential and a non-local optical potential which is definite. The resulting phase shifts have rigorous lower bounds and the convergence is much faster than those obtained without the modification of the target function. Final results will be presented at the conference.

  18. Relating P-wave attenuation to permeability

    SciTech Connect

    Akbar, N.; Dvorkin, J.; Nur, A. . Dept. of Geophysics)

    1993-01-01

    To relate P-wave attenuation to permeability, the authors examine a three-dimensional (3-D) theoretical model of a cylindrical pore filled with viscous fluid and embedded in an infinite isotropic elastic medium. They calculate both attenuation and permeability as functions of the direction of wave propagation. Attenuation estimates are based on the squirt flow mechanism; permeability is calculated using the Kozeny-Carmen relation. They find that in the case when a plane P-wave propagates parallel to this orientation (Q[sup [minus]1][delta] = 90[degree]), attenuation is always higher than when a wave propagates parallel to this orientation (Q[sup [minus]1][delta] = 0[degree]). The ratio of these two attenuation values Q[sup [minus]1][delta] = 90[degree]/Q[sup [minus]1] = 0[degree] increases with an increasing pore radius and decreasing frequency and saturation. By changing permeability, varying the radius of the pore, they find that the permeability-attenuation relation is characterized by a peak that shifts toward lower permeabilities as frequency decreases. Therefore, the attenuation of a low-frequency wave decreases with increasing permeability. They observe a similar trend on relations between attenuation and permeability experimentally obtained on sandstone samples.

  19. 62-TeV center of mass hadron collider with superbunch beams

    SciTech Connect

    Ryuji Yamada et al.

    2001-11-05

    The scheme of a 62-TeV center of mass p-p collider with superbunch beams at Fermilab is proposed as a practical and realistically achievable future project. It will be built in two stages, using the same tunnel, first with a 2 Tesla low field magnet collider ring and later with a 10 Tesla high field magnet collider ring. Both low and high field magnets have twin bore aperture and will be installed in the tunnel with the circumference of 87.25 km. In each bore a proton beam is accelerated, using induction cavities to increase luminosity. In the first stage they install a 7 TeV accelerator ring with operating field of 2 Tesla, based on the superferric transmission-line design. This ring will be operated at a 14-TeV center of mass collider. This will have the same energy as the LHC, but it will have 15 times higher luminosity, namely 1.5 x 10{sup 35}/cm{sup 2}/sec. The estimated synchrotron radiation is negligible with this machine. The existing Fermilab accelerator system, including the 150 GeV main injector, will be used as the injector system. Its rough cost estimation and schedule for this first stage are presented. In the second stage proton beams are accelerated, also using induction cavities up to 31 TeV with the 10 Tesla dipole magnets. The counter circulating beams will collide with the 62-TeV center of mass energy. With the superbunch beams they can expect the luminosity can be increased about 15 times more than the conventional method with RF cavities. It will be 10{sup 35}/cm{sup 2}/sec. In the second stage, the synchrotron radiation power will be about 12 W/m, and they need an elaborated beam screen.

  20. Measurements of the center-of-mass energies at BESIII via the di-muon process

    NASA Astrophysics Data System (ADS)

    Ablikim, M.; N. Achasov, M.; C. Ai, X.; Albayrak, O.; Albrecht, M.; J. Ambrose, D.; Amoroso, A.; An, F. F.; An, Q.; Bai, J. Z.; Baldini, Ferroli R.; Ban, Y.; Bennett, D. W.; Bennett, J. V.; Bertani, M.; Bettoni, D.; Bian, J. M.; Bianchi, F.; Boger, E.; Boyko, I.; Briere, R. A.; Cai, H.; Cai, X.; Cakir, O.; Calcaterra, A.; Cao, G. F.; Cetin, S. A.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, H. Y.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, X.; Chen, X. R.; Chen, Y. B.; Cheng, H. P.; Chu, X. K.; Cibinetto, G.; Dai, H. L.; Dai, J. P.; Dbeyssi, A.; Dedovich, D.; Y. Deng, Z.; Denig, A.; Denysenko, I.; Destefanis, M.; De Mori, F.; Ding, Y.; Dong, C.; Dong, J.; Dong, L. Y.; Dong, M. Y.; Du, S. X.; Duan, P. F.; Fan, J. Z.; Fang, J.; Fang, S. S.; Fang, X.; Fang, Y.; Fava, L.; Feldbauer, F.; Felici, G.; Feng, C. Q.; Fioravanti, E.; Fritsch, M.; Fu, C. D.; Gao, Q.; Gao, X. L.; Gao, X. Y.; Gao, Y.; Gao, Z.; Garzia, I.; Goetzen, K.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, Y.; Guo, Y. P.; Haddadi, Z.; Hafner, A.; Han, S.; Q. Hao, X. Q.; Harris, F. A.; He, K. L.; Held, T.; Heng, Y. K.; Hou, Z. L.; Hu, C.; Hu, H. M.; Hu, J. F.; Hu, T.; Hu, Y.; Huang, G. M.; Huang, G. S.; Huang, J. S.; Huang, X. T.; Huang Y.; Hussain, T.; Ji, Q.; Ji, Q. P.; Ji, X. B.; Ji, X. L.; Jiang, L. W.; Jiang, X. S.; Jiang, X. Y.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Johansson, T.; Julin, A.; Kalantar-Nayestanaki, N.; Kang, X. L.; Kang, X. S.; Kavatsyuk, M.; Ke, B. C.; Kiese, P.; Kliemt, R.; Kloss, B.; Kolcu, O. B.; Kopf, B.; Kornicer, M.; Kühn, W.; Kupsc, A.; Lange, J. S.; Lara, M.; Larin, P.; Leng, C.; Li, C.; Cheng, Li; Li, D. M.; Li, F.; Li, F. Y.; Li, G.; Li, H. B.; Li, J. C.; Li, Jin; Li, K.; Li, K.; Li, Lei; Li, P. R.; Li, T.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. M.; Li, X. N.; Li, X. Q.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Lin, X.; Liu, B. J.; Liu, C. X.; Liu, D.; Liu, F. H.; Fang, Liu; Feng, Liu; Liu, H. B.; Liu, H. H.; Liu, H. H.; Liu, H. M.; Liu, J.; Liu, J. B.; Liu, J. P.; Liu, J. Y.; Liu, K.; Liu, K. Y.; Liu, L. D.; Liu, P. L.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, Y. B.; Liu, Z. A.; Liu, Zhiqing; Loehner, H.; Lou, X. C.; Lu, H. J; Lu, J. G.; Lu, Y.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lyu, X. R.; Ma, F. C.; Ma, H. L.; Ma, L. L.; Ma, Q. M.; Ma, T.; Ma, X. N.; Ma, X. Y.; Maas, F. E.; Maggiora, M.; Mao, Y. Y.; Mao, Z. P.; Marcello, S.; Messchendorp, J. G.; Min, J.; Mitchell, R. E.; Mo, X. H.; Mo, Y. J.; Morales Morales, C.; Moriya, K.; Muchnoi, N. Yu.; Muramatsu, H.; Nefedov, Y.; Nerling, F.; Nikolaev, I. B.; Ning, Z.; Nisar, S.; Niu, S. L.; Niu, X. Y.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Pan, Y.; Patteri, P.; Pelizaeus, M.; Peng, H. P.; Peters, K.; Pettersson, J.; Ping, J. L.; Ping, R. G.; Poling, R.; Prasad, V.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, L. Q.; Qin, N.; Qin, X. S.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Redmer, C. F.; Ripka, M.; Rong, G.; Rosner, Ch.; Ruan, X. D.; Santoro, V.; Sarantsev, A. A.; Savrié, M.; Schoenning, B. K.; Schumann, S.; Shan, W.; Shao, M.; Shen, C. P.; Shen, P. X.; Shen, X. Y.; Sheng, H. Y.; Song, W. M.; Song, X. Y.; Sosio, S.; Spataro, S.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Tapan, I.; Thorndike, E. H.; Tiemens, M.; Ullrich, M.; Uman, I.; Varner, G. S.; Wang, B.; Wang, D.; Wang, D. Y.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, S. G.; Wang, W.; Wang, W. P.; Wang, X. F.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. H.; Wang, Z. Y.; Weber, T.; Wei, D. H.; Wei, J. B.; Weidenkaff, P.; Wen, S. P.; Wiedner, U.; Wolke, M.; Wu, L. H.; Wu, Z.; Xia, L.; Xia, L. G.; Xia, Y.; Xiao, D.; Xiao, H.; Xiao, Z. J.; Xie, Y. G.; Xiu, Q. L.; Xu, G. F.; Xu, L.; Xu, Q. J.; Xu, X. P.; Yan, L.; Yan, W. B.; Yan, W. C.; Yan, Y. H.; Yang, H. J.; Yang, H. X.; Yang, L.; Yang, Y.; Yang, Y. X.; Ye, M.; Ye, M. H.; Yin, J. H.; Yu, B. X.; Yu, C. X.; Yu, J. S.; Yuan, C. Z.; Yuan, W. L.; Yuan, Y.; Yuncu, A.; Zafar, A. A.; Zallo, A.; Zeng, A. Y.; Zeng, Z.; Zhang, B. X.; Zhang, B. Y.; Zhang, C.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J. J.; Zhang, J. L.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, K.; Zhang, L.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. N.; Zhang, Y. H.; Zhang, Y. T.; Zhang, Yu; Zhang, Z. H.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, J. W.; Zhao, J. Y.; Zhao, J. Z.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, Q. W.; Zhao, S. J.; Zhao, T. C.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, W. J.; Zheng, Y. H.; Zhong, B.; Zhou, L.; Zhou, X.; Zhou, X. K.; Zhou, X. R.; Zhou, X. Y.; Zhu, K.; Zhu, K. J.; Zhu, S.; , S. H.; Zhu, X. L.; Zhu, Y. C.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zotti, L.; Zou, B. S.; Zou, J. H.; BESIII collaboration

    2016-06-01

    From 2011 to 2014, the BESIII experiment collected about 5 fb‑1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process e+e‑ → γISR/FSRμ+μ‑, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of the time during data taking. Supported by National Key Basic Research Program of China (2015CB856700), National Natural Science Foundation of China (11125525, 11235011, 11322544, 11335008, 11425524, Y61137005C), Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program, CAS Center for Excellence in Particle Physics (CCEPP), Collaborative Innovation Center for Particles and Interactions (CICPI), Joint Large-Scale Scientific Facility Funds of NSFC and CAS (11179007, U1232201, U1332201), CAS (KJCX2-YW-N29, KJCX2-YW-N45), 100 Talents Program of CAS, National 1000 Talents Program of China, INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology, German Research Foundation DFG (Collaborative Research Center CRC-1044), Istituto Nazionale di Fisica Nucleare, Italy, Ministry of Development of Turkey (DPT2006K-120470), Russian Foundation for Basic Research (14-07-91152), Swedish Research Council, U. S. Department of Energy (DE-FG02-04ER41291, DE-FG02-05ER41374, DE-FG02-94ER40823, DESC0010118), U.S. National Science Foundation, University of Groningen (RuG) and Helmholtzzentrum fuer Schwerionenforschung GmbH (GSI), Darmstadt, WCU Program of National Research Foundation of Korea (R32-2008-000-10155-0).

  1. The main properties and peculiarities of the Earth's motion relative to the center of mass

    NASA Astrophysics Data System (ADS)

    Klimov, D. M.; Akulenko, L. D.; Kumakshev, S. A.

    2014-10-01

    The methods of theoretical and celestial mechanics and mathematical statistics have been used to prove that the Earth's motion relative to the center of mass, the polar wobble, in the principal approximation is a combination of two circumferences with a slow trend in the mean position corresponding to the annual and Chandler components. It has been established that the parameters (amplitude and phase shift) of the annual wobble are stable, while those of the Chandler component are less stable and undergo significant variations over the observed time intervals. It has been proven that the behavior of these polar motion parameters is attributable to the gravitational-tidal mechanisms of their excitation.

  2. Center-of-mass and internal motion of excitons in quantum wires

    NASA Astrophysics Data System (ADS)

    Glutsch, S.; Bechstedt, F.

    The properties of excitons, which are optically excited in single or coupled quantum wires, are studied within the effective-mass approximation. The two-particle wave functions and energies obey a Schrödinger equation with screened Coulomb interaction of electron and hole and their corresponding wire confinement potentials. This equation is approximately separated into an equation for the center-of-mass motion and another one more or less for the internal motion of the electron hole pairs. This allows a representation of absorption and luminescence spectra near a quantum-well exciton transition by a generalized Elliott formula.

  3. Geodetic results from ISAGEX data. [for obtaining center of mass coordinates for geodetic camera sites

    NASA Technical Reports Server (NTRS)

    Marsh, J. G.; Douglas, B. C.; Walls, D. M.

    1974-01-01

    Laser and camera data taken during the International Satellite Geodesy Experiment (ISAGEX) were used in dynamical solutions to obtain center-of-mass coordinates for the Astro-Soviet camera sites at Helwan, Egypt, and Oulan Bator, Mongolia, as well as the East European camera sites at Potsdam, German Democratic Republic, and Ondrejov, Czechoslovakia. The results are accurate to about 20m in each coordinate. The orbit of PEOLE (i=15) was also determined from ISAGEX data. Mean Kepler elements suitable for geodynamic investigations are presented.

  4. The earth's rotation. [three dimensional rotation about its center of mass

    NASA Technical Reports Server (NTRS)

    Rochester, M. G.

    1975-01-01

    The state-of-the-art technology in the study of the three dimensional rotation of the earth about its center of mass is summarized. A survey of appropriate reference frames and problems involved in defining them is given along with an outline of the accuracy with which the earth's rotation can be measured relative to these frames. The various spectral features of changes in the axis orientation and spin rate of the solid earth and the physical mechanisms known or likely to effect and/or affect them are discussed.

  5. Precise determination of earth's center of mass using measurements from the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Vigue, Yvonne; Lichten, Stephen M.; Blewitt, Geoffrey; Heflin, Michael B.; Malla, Rajendra P.

    1992-01-01

    Global Positioning System (GPS) data from a worldwide geodetic experiment were collected during a 3-week period early in 1991. Geocentric station coordinates were estimated using the GPS data, thus defining a dynamically determined reference frame origin which should coincide with the earth center of mass, or geocenter. The 3-week GPS average geocenter estimates agree to 7-13 cm with geocenter estimates determined from satellite laser ranging, a well-established technique. The RMS of daily GPS geocenter estimates were 4 cm for x and y, and 30 cm for z.

  6. Comparison of nonmesonic hypernuclear decay rates computed in laboratory and center-of-mass coordinates

    SciTech Connect

    De Conti, C.; Barbero, C.; Galeão, A. P.; Krmpotić, F.

    2014-11-11

    In this work we compute the one-nucleon-induced nonmesonic hypernuclear decay rates of {sub Λ}{sup 5}He, {sub Λ}{sup 12}C and {sub Λ}{sup 13}C using a formalism based on the independent particle shell model in terms of laboratory coordinates. To ascertain the correctness and precision of the method, these results are compared with those obtained using a formalism in terms of center-of-mass coordinates, which has been previously reported in the literature. The formalism in terms of laboratory coordinates will be useful in the shell-model approach to two-nucleon-induced transitions.

  7. Finite frequency global P wave tomography

    NASA Astrophysics Data System (ADS)

    Montelli, R.; Nolet, G.; Masters, G.; Dahlen, F. A.; Hung, S.-H.

    2003-04-01

    The travel time of a finite frequency wave is sensitive to velocity structure off the geometrical ray within a volume known as the Fresnel zone. We compute 3D travel time sensitivity efficiently by using the paraxial approximation in conjunction with ray theory and the Born approximation (Dahlen et al., 2000) to invert global travel times of long-period compressional waves. Our data set consists of 67540 P and 20266 PP-P travel times measured by cross-correlation. The sensitivity of a broad-band P arrival time resembles a hollow-banana surrounding the unperturbed path with sensitivity being zero on the ray. Typical widths of sensitivity kernels at the turning point are about 1000 km and 1300 km for a P wave at 60o and 80o epicentral distance, respectively. The region of insensitivity around the geometrical ray is small near the source and the receiver but can extend to about 400 km near the turning point for a P wave at 80o epicentral distance. Because of the minimax nature, surface reflected PP waves show a much more complicated shape of the sensitivity region, with the banana-doughnut shape replaced by a saddle-shaped region upon passage of a caustic. Not surprisingly, the introduction of such complicated sensitivity has consequences for the final tomographic images. We compare tomographic models inverted with the new method and with the more standard technique of ray theory for the same data fit (i.e. same χ2) and each smoothed to resolve very similar length scales. Depending on depth and size of the anomaly, amplitudes of the velocity perturbations in finite frequency images are on average 30%-60% higher than those obtained with ray theory. This demonstrates a major shortcoming of ray theory. It is not possible to neglect wavefront healing effect, as ray theory does. The images obtained by inverting long-period waves provide unambiguous evidence that a limited number of hot-spots are fed by plumes originating in the lower mantle. To better constrain the P wave

  8. Holographic p-wave superconductor with disorder

    NASA Astrophysics Data System (ADS)

    Areán, D.; Farahi, A.; Pando Zayas, L. A.; Salazar Landea, I.; Scardicchio, A.

    2015-07-01

    We implement the effects of disorder on a holographic p-wave superconductor by introducing a random chemical potential which defines the local energy of the charge carriers. Since there are various possibilities for the orientation of the vector order parameter, we explore the behavior of the condensate in the parallel and perpendicular directions to the introduced disorder. We clarify the nature of various branches representing competing solutions and construct the disordered phase diagram. We find that moderate disorder enhances superconductivity as determined by the value of the condensate. Though we mostly focus on uncorrelated noise, we also consider a disorder characterized by its spectral properties and study in detail its influence on the spectral properties of the condensate and charge density. We find fairly universal responses of the resulting power spectra characterized by linear functions of the disorder power spectrum.

  9. Upper bound on the center-of-mass energy of the collisional Penrose process

    NASA Astrophysics Data System (ADS)

    Hod, Shahar

    2016-08-01

    Following the interesting work of Bañados, Silk, and West (2009) [6], it is repeatedly stated in the physics literature that the center-of-mass energy, Ec.m, of two colliding particles in a maximally rotating black-hole spacetime can grow unboundedly. For this extreme scenario to happen, the particles have to collide at the black-hole horizon. In this paper we show that Thorne's famous hoop conjecture precludes this extreme scenario from occurring in realistic black-hole spacetimes. In particular, it is shown that a new (and larger) horizon is formed before the infalling particles reach the horizon of the original black hole. As a consequence, the center-of-mass energy of the collisional Penrose process is bounded from above by the simple scaling relation Ec.mmax / 2 μ ∝(M / μ) 1 / 4, where M and μ are respectively the mass of the central black hole and the proper mass of the colliding particles.

  10. A simplified marker set to define the center of mass for stability analysis in dynamic situations.

    PubMed

    Tisserand, R; Robert, T; Dumas, R; Chèze, L

    2016-07-01

    The extrapolated center of mass (XCoM), a valuable tool to assess balance stability, involves defining the whole body center of mass (CoMWB). However, accurate three-dimensional estimation of the CoMWB is time consuming, a severe limitation in certain applications. In this study, twenty-four subjects (young and elderly, male and female) performed three different balance tasks: quiet standing, gait and balance recovery. Three different models, based on a segmental method, were used to estimate the three-dimensional CoMWB absolute position during these movements: a reference model based on 38 markers, a simplified 13-marker model and a single marker (sacral) model. CoMWB and XCoM estimations from the proposed simplified model came closer to the reference model than estimations from the sacral marker model. It remained accurate for dynamic tasks, where the sacral marker model proved inappropriate. The simplified model proposed here yields accurate three-dimensional estimation of both the CoMWB and the XCoM with a limited number of markers. Importantly, using this model would reduce the experimental and post-processing times for future balance studies assessing dynamic stability in humans. PMID:27477710

  11. An Analysis of Body Center of Mass Movement during Walking for Power Asisst of Paraplegic Gait

    NASA Astrophysics Data System (ADS)

    Kagawa, Takahiro; Yamashina, Hideki; Uno, Yoji

    An efficient and stable gait control is an essential problem to develop a legged locomotor device for paraplegics. In this study, we investigate a necessary condition of the ballistic walking to avoid a backward balance loss. The condition derived by an inverted pendulum model is represented as a simple relationship between a position and velocity of a body center of mass at toe-off. The condition was validated through simulation experiments of a 7-link musculoskeletal model and gait measurement experiments of normal and paraplegic subjects. The results of the model simulation showed a good agreement with some predictions of the inverted pendulum model. The measured center of mass trajectories of normal and paraplegic gaits were satisfied with the necessary condition. These results suggest that the necessary condition is effective to avoid a backward falling during walking. In addition, energy input was required in a double support phase while the trajectory followed the ballistic movement of the inverted pendulum in a single support phase for a normal subject. These results suggest that a power assist control to be satisfied with the necessary condition during a double support phase and a ballistic gait generation during a single support phase are required for a paraplegic locomotor with efficiency and stability.

  12. Fermion Superfluidity

    NASA Technical Reports Server (NTRS)

    Strecker, Kevin; Truscott, Andrew; Partridge, Guthrie; Chen, Ying-Cheng

    2003-01-01

    Dual evaporation gives 50 million fermions at T = 0.1 T(sub F). Demonstrated suppression of interactions by coherent superposition - applicable to atomic clocks. Looking for evidence of Cooper pairing and superfluidity.

  13. Is the regulation of the center of mass maintained during leg movement under microgravity conditions?

    PubMed

    Mouchnino, L; Cincera, M; Fabre, J C; Assaiante, C; Amblard, B; Pedotti, A; Massion, J

    1996-08-01

    1. Investigations on stance regulation have already suggested that the body's center of mass is the variable controlled by the CNS to maintain equilibrium. The aim of this study was to determine how the center of mass of the body is regulated when leg movements are made under different gravitoinertial force conditions. 2. Kinematic and electromyographic (EMG) recordings were made during both straight-and-level flight (earth-normal gravity condition, nG) and periods of weightlessness in parabolic flight (microgravity condition, microG). The standing subjects were restrained to the floor (kept from floating away in microG) and were instructed to raise one leg laterally to an angle of 45 degrees as fast as possible. 3. Two modes of center of mass (CM) control were identified during leg movement in nG: a "shift mode" and a "stabilization mode." The shift mode served to transfer the CM toward the supporting side before the leg raising, and it preceded the phase of single limb support. The stabilization mode took place after the CM shift was completed and was aimed at stabilizing the CM during raising of the leg. In this phase, the movement of the raising leg is counterbalanced by a lateral inclination of the trunk in the opposite direction. As a consequence, CM position did not change with respect to the position reached before the leg raising, and its projection on the ground remained within the support area delineated by the stance foot. 4. Under microG, the CM position did not change before the leg raising. Moreover, gastrocnemius medialis activity observed in the moving leg under nG, preceding the initiation of the body weight transfer toward the supporting leg, was greatly reduced. While the leg is raising, the simultaneous and opposite lateral trunk movement was still present in microG. 5. Results suggest that the body weight transfer corresponding to the shift mode, might depend on the gravity constraints, whereas the stabilization mode, which remains unchanged

  14. Estimation of Center of Mass Trajectory using Wearable Sensors during Golf Swing.

    PubMed

    Najafi, Bijan; Lee-Eng, Jacqueline; Wrobel, James S; Goebel, Ruben

    2015-06-01

    This study suggests a wearable sensor technology to estimate center of mass (CoM) trajectory during a golf swing. Groups of 3, 4, and 18 participants were recruited, respectively, for the purpose of three validation studies. Study 1 examined the accuracy of the system to estimate a 3D body segment angle compared to a camera-based motion analyzer (Vicon®). Study 2 assessed the accuracy of three simplified CoM trajectory models. Finally, Study 3 assessed the accuracy of the proposed CoM model during multiple golf swings. A relatively high agreement was observed between wearable sensors and the reference (Vicon®) for angle measurement (r > 0.99, random error <1.2° (1.5%) for anterior-posterior; <0.9° (2%) for medial-lateral; and <3.6° (2.5%) for internal-external direction). The two-link model yielded a better agreement with the reference system compared to one-link model (r > 0.93 v. r = 0.52, respectively). On the same note, the proposed two-link model estimated CoM trajectory during golf swing with relatively good accuracy (r > 0.9, A-P random error <1cm (7.7%) and <2cm (10.4%) for M-L). The proposed system appears to accurately quantify the kinematics of CoM trajectory as a surrogate of dynamic postural control during an athlete's movement and its portability, makes it feasible to fit the competitive environment without restricting surface type. Key pointsThis study demonstrates that wearable technology based on inertial sensors are accurate to estimate center of mass trajectory in complex athletic task (e.g., golf swing)This study suggests that two-link model of human body provides optimum tradeoff between accuracy and minimum number of sensor module for estimation of center of mass trajectory in particular during fast movements.Wearable technologies based on inertial sensors are viable option for assessing dynamic postural control in complex task outside of gait laboratory and constraints of cameras, surface, and base of support. PMID:25983585

  15. Estimation of Center of Mass Trajectory using Wearable Sensors during Golf Swing

    PubMed Central

    Najafi, Bijan; Lee-Eng, Jacqueline; Wrobel, James S.; Goebel, Ruben

    2015-01-01

    This study suggests a wearable sensor technology to estimate center of mass (CoM) trajectory during a golf swing. Groups of 3, 4, and 18 participants were recruited, respectively, for the purpose of three validation studies. Study 1 examined the accuracy of the system to estimate a 3D body segment angle compared to a camera-based motion analyzer (Vicon®). Study 2 assessed the accuracy of three simplified CoM trajectory models. Finally, Study 3 assessed the accuracy of the proposed CoM model during multiple golf swings. A relatively high agreement was observed between wearable sensors and the reference (Vicon®) for angle measurement (r > 0.99, random error <1.2° (1.5%) for anterior-posterior; <0.9° (2%) for medial-lateral; and <3.6° (2.5%) for internal-external direction). The two-link model yielded a better agreement with the reference system compared to one-link model (r > 0.93 v. r = 0.52, respectively). On the same note, the proposed two-link model estimated CoM trajectory during golf swing with relatively good accuracy (r > 0.9, A-P random error <1cm (7.7%) and <2cm (10.4%) for M-L). The proposed system appears to accurately quantify the kinematics of CoM trajectory as a surrogate of dynamic postural control during an athlete’s movement and its portability, makes it feasible to fit the competitive environment without restricting surface type. Key points This study demonstrates that wearable technology based on inertial sensors are accurate to estimate center of mass trajectory in complex athletic task (e.g., golf swing) This study suggests that two-link model of human body provides optimum tradeoff between accuracy and minimum number of sensor module for estimation of center of mass trajectory in particular during fast movements. Wearable technologies based on inertial sensors are viable option for assessing dynamic postural control in complex task outside of gait laboratory and constraints of cameras, surface, and base of support. PMID:25983585

  16. Center of mass and spin for isolated sources of gravitational radiation

    NASA Astrophysics Data System (ADS)

    Kozameh, Carlos N.; Quiroga, Gonzalo D.

    2016-03-01

    We define the center of mass and spin of an isolated system in general relativity. The resulting relationships between these variables and the total linear and angular momentum of the gravitational system are remarkably similar to their Newtonian counterparts, though only variables at the null boundary of an asymptotically flat spacetime are used for their definition. We also derive equations of motion linking their time evolution to the emitted gravitational radiation. The results are then compared to other approaches. In particular, one obtains unexpected similarities as well as some differences with results obtained in the post-Newtonian literature. These equations of motion should be useful when describing the radiation emitted by compact sources, such as coalescing binaries capable of producing gravitational kicks, supernovas, or scattering of compact objects.

  17. Stability Control of Grasping Objects with Different Locations of Center of Mass and Rotational Inertia

    PubMed Central

    Slota, Gregory P.; Suh, Moon Suk; Latash, Mark L.; Zatsiorsky, Vladimir M.

    2012-01-01

    The objective of this study was to observe how the digits of the hand adjust to varying location of the center of mass (CoM) above/below the grasp and rotational inertia (RI) of a hand held object. Such manipulations do not immediately affect the equilibrium equations while stability control is affected. Participants were instructed to hold a handle, instrumented with five force/torque transducers and a 3-D rotational tilt sensor, while either the location of the CoM or the RI values were adjusted. On the whole, people use two mechanisms to adjust to the changed stability requirements; they increase the grip force and redistribute the total moment between the normal and tangential forces offsetting internal torques. The increase in grip force, an internal force, and offsetting internal torques allows for increases in joint and hand rotational apparent stiffness while not creating external forces/torques which would unbalance the equations of equilibrium. PMID:22456054

  18. Falling paper: Navier-Stokes solutions, model of fluid forces, and center of mass elevation.

    PubMed

    Pesavento, Umberto; Wang, Z Jane

    2004-10-01

    We investigate the problem of falling paper by solving the two dimensional Navier-Stokes equations subject to the motion of a free-falling body at Reynolds numbers around 10(3). The aerodynamic lift on a tumbling plate is found to be dominated by the product of linear and angular velocities rather than velocity squared, as appropriate for an airfoil. This coupling between translation and rotation provides a mechanism for a brief elevation of center of mass near the cusplike turning points. The Navier-Stokes solutions further provide the missing quantity in the classical theory of lift, the instantaneous circulation, and suggest a revised model for the fluid forces. PMID:15524800

  19. An element formulation for perturbed motion about the center of mass

    NASA Technical Reports Server (NTRS)

    Donaldson, J. D.; Jezewski, D. J.

    1977-01-01

    The perturbed motion of a rigid body about its center of mass, is formulated in terms of the six elements: l, the magnitude of the angular momentum vector; h, the total energy; delta and epsilon, two linear functions of the independent variable; and psi(1) and theta (1), two Euler angles that orientate the inertial frame with respect to the unperturbed solution. Solutions from the element formulation and the original Euler equations are numerically compared using shuttle-type data. For applied torques smaller than a given magnitude, the element formulation produced the following results: (1) larger step sizes in the numerical integration of the differential equations, resulting in an overall computational time-saving, and (2) more significant figures of accuracy in the computation of the variables describing the state of the rigid body.

  20. Center of mass motion in swimming fish: effects of speed and locomotor mode during undulatory propulsion.

    PubMed

    Xiong, Grace; Lauder, George V

    2014-08-01

    Studies of center of mass (COM) motion are fundamental to understanding the dynamics of animal movement, and have been carried out extensively for terrestrial and aerial locomotion. But despite a large amount of literature describing different body movement patterns in fishes, analyses of how the center of mass moves during undulatory propulsion are not available. These data would be valuable for understanding the dynamics of different body movement patterns and the effect of differing body shapes on locomotor force production. In the present study, we analyzed the magnitude and frequency components of COM motion in three dimensions (x: surge, y: sway, z: heave) in three fish species (eel, bluegill sunfish, and clown knifefish) swimming with four locomotor modes at three speeds using high-speed video, and used an image cross-correlation technique to estimate COM motion, thus enabling untethered and unrestrained locomotion. Anguilliform swimming by eels shows reduced COM surge oscillation magnitude relative to carangiform swimming, but not compared to knifefish using a gymnotiform locomotor style. Labriform swimming (bluegill at 0.5 body lengths/s) displays reduced COM sway oscillation relative to swimming in a carangiform style at higher speeds. Oscillation frequency of the COM in the surge direction occurs at twice the tail beat frequency for carangiform and anguilliform swimming, but at the same frequency as the tail beat for gymnotiform locomotion in clown knifefish. Scaling analysis of COM heave oscillation for terrestrial locomotion suggests that COM heave motion scales with positive allometry, and that fish have relatively low COM oscillations for their body size. PMID:24925455

  1. Fermionic networks

    NASA Astrophysics Data System (ADS)

    Javarone, Marco Alberto

    2016-08-01

    We study the structure of fermionic networks, i.e. a model of networks based on the behavior of fermionic gases, and we analyze dynamical processes over them. In this model, particle dynamics have been mapped to the domain of networks, hence a parameter representing the temperature controls the evolution of the system. In doing so, it is possible to generate adaptive networks, i.e. networks whose structure varies over time. As shown in previous works, networks generated by quantum statistics can undergo critical phenomena as phase transitions and, moreover, they can be considered as thermodynamic systems. In this study, we analyze fermionic networks and opinion dynamics processes over them, framing this network model as a computational model useful to represent complex and adaptive systems. Results highlight that a strong relation holds between the gas temperature and the structure of the achieved networks. Notably, both the degree distribution and the assortativity vary as the temperature varies, hence we can state that fermionic networks behave as adaptive networks. On the other hand, it is worth to highlight that we did not finding relation between outcomes of opinion dynamics processes and the gas temperature. Therefore, although the latter plays a fundamental role in gas dynamics, on the network domain, its importance is related only to structural properties of fermionic networks.

  2. P Wave Dispersion and Maximum P Wave Duration Are Associated with Renal Outcomes in Chronic Kidney Disease

    PubMed Central

    Huang, Jiun-Chi; Wei, Shu-Yi; Chen, Szu-Chia; Chang, Jer-Ming; Hung, Chi-Chih; Su, Ho-Ming; Hwang, Shang-Jyh; Chen, Hung-Chun

    2014-01-01

    P wave parameters measured by 12-lead electrocardiogram (ECG) are commonly used as a noninvasive tool to evaluate left atrial enlargement. This study was designed to assess whether P wave parameters were associated with renal outcomes in chronic kidney disease (CKD) patients. This longitudinal study enrolled 439 patients with CKD stages 3–5. Renal end points were defined as the commencement of dialysis or death. Change in renal function was measured using the estimated glomerular filtration rate (eGFR) slope. We measured two ECG P wave parameters corrected for heart rate, i.e., corrected P wave dispersion and corrected maximum P wave duration. The values of P wave dispersion and maximum P wave duration were 88.8±21.7 ms and 153.3±21.7 ms, respectively. During the follow-up period (mean, 25.2 months), 95 patients (21.6%) started hemodialysis and 30 deaths (6.8%) were recorded. Multivariate Cox regression analysis identified that increased P wave dispersion [hazard ratio (HR), 1.020; 95% confidence interval (CI), 1.009–1.032; P<0.001] and maximum P wave duration (HR, 1.013; 95% CI, 1.003–1.024; P = 0.012) were associated with progression to renal end points. Furthermore, increased P wave dispersion (unstandardized coefficient β = –0.016; P = 0.037) and maximum P wave duration (unstandardized coefficient β = –0.014; P = 0.040) were negatively associated with the eGFR slope. We demonstrated that increased P wave dispersion and maximum P wave duration were associated with progression to the renal end points of dialysis or death and faster renal function decline in CKD patients. Screening CKD patients on the basis of P wave dispersion and maximum P wave duration may help identify patients at high risk for worse renal outcomes. PMID:25006682

  3. Change in P wave morphology after convergent atrial fibrillation ablation.

    PubMed

    Shrestha, Suvash; Chen, On; Greene, Mary; John, Jinu Jacob; Greenberg, Yisachar; Yang, Felix

    2016-01-01

    Convergent atrial fibrillation ablation involves extensive epicardial as well as endocardial ablation of the left atrium. We examined whether it changes the morphology of the surface P wave. We reviewed electrocardiograms of 29 patients who underwent convergent ablation for atrial fibrillation. In leads V1, II and III, we measured P wave duration, area and amplitude before ablation, and at 1, 3 and 6 months from ablation. After ablation, there were no significant changes in P wave amplitude, area, or duration in leads II and III. There was a significant reduction in the area of the terminal negative deflection of the P wave in V1 from 0.38 mm(2) to 0.13 mm(2) (p = 0.03). There is also an acute increase in the amplitude and duration of the positive component of the P wave in V1 followed by a reduction in both by 6 months. Before ablation, 62.5% of the patients had biphasic P waves in V1. In 6 months, only 39.2% of them had biphasic P waves. Hybrid ablation causes a reduction of the terminal negative deflection of the P wave in V1 as well as temporal changes in the duration and amplitude of the positive component of the P wave in V1. This likely reflects the reduced electrical contribution of the posterior left atrium after ablation as well as anatomical and autonomic remodeling. Recognition of this altered sinus P wave morphology is useful in the diagnosis of atrial arrhythmias in this patient population. PMID:27485559

  4. Paired States of Composite Fermions

    NASA Astrophysics Data System (ADS)

    Bonesteel, N. E.

    2002-03-01

    There is compelling theoretical evidence(R. Morf, Phys. Rev. Lett. 80), 1505 (1998). that the ν=5/2 fractional quantum Hall state is a Moore-Read state(G. Moore and N. Read, Nucl. Phys. B 360), 362 (1991). -- a state which can be viewed as a spin-polarized p-wave `superconductor' of composite fermions. The question remains, how can one test this hypothesis experimentally? To address this we have developed a semi-phenomenological description of this state in which the Halperin-Lee-Read(B.I. Halperin, P.A. Lee, and N. Read, Phys. Rev. B 47), 7312 (1993). theory of the half-filled Landau level is modified by adding a p-wave pairing interaction between composite fermions by hand. The electromagnetic response functions for the resulting mean-field superconducting state are then calculated and used in an RPA calculation of the physical electronic response. For a clean enough sample, and for q << k_f, the transverse electromagnetic response function for composite fermions is governed by type-II coherence factors and shows a `Hebel-Slichter'-like peak as a function of temperature for low enough frequency. The possibility (and potential difficulties) of observing this peak indirectly in surface-acoustic-wave propagation experiments will be discussed. The observation of such a coherence peak would provide strong evidence of BCS pairing in the 5/2 state. Work supported by US DOE Grant No. DE-FG02-97ER45639. Work done in collaboration with K.C. Foster (FSU) and S.H. Simon (Lucent). note

  5. ADAPTIVE CONTROL OF CENTER OF MASS (GLOBAL) MOTION AND ITS JOINT (LOCAL) ORIGIN IN GAIT

    PubMed Central

    Yang, Feng; Pai, Yi-Chung

    2014-01-01

    Dynamic gait stability can be quantified by the relationship of the motion state (i.e. the position and velocity) between the body center of mass (COM) and its base of support (BOS). Humans learn how to adaptively control stability by regulating the absolute COM motion state (i.e., its position and velocity) or by controlling the BOS (through stepping) in a predictable manner, or by doing both simultaneously following an external perturbation that disrupts their regular relationship. Post repeated-slip perturbation training, for instance, older adults learned to forward shift their COM position while walking with a reduced step length, hence reduced their likelihood of falls. How and to what extent each individual joint influences such adaptive alterations is mostly unknown. A three-dimensional individualized human kinematic model was established. Based on the human model, sensitivity analysis was used to systematically quantify the influence of each lower limb joint on the COM position relative to the BOS and the step length during gait. It was found that the leading foot had the greatest effect on regulating the COM position relative to the BOS; and both hips bear the most influence on the step length. These findings could guide cost-effective but efficient fall-reduction training paradigm among older population. PMID:24998991

  6. Kinematics and center of mass mechanics during terrestrial locomotion in northern lapwings (Vanellus vanellus, Charadriiformes).

    PubMed

    Nyakatura, J A; Andrada, E; Grimm, N; Weise, H; Fischer, M S

    2012-11-01

    Avian bipedalism is best studied in derived walking/running specialists. Here, we use kinematics and center of mass (CoM) mechanical energy patterns to investigate gait transitions of lapwings-migratory birds that forage on the ground, and therefore may need a trade-off between the functional demands of terrestrial locomotion and long distance flights. The animals ran on a treadmill while high-speed X-ray videos were recorded within the sustainable speed range. Instantaneous CoM mechanics were computed from integrating kinematics and body segment properties. Lapwings exhibit similar locomotor characteristics to specialized walking/running birds, but have less distinct gaits. At slow speeds no clear separation between vaulting (i.e., walking) and bouncing (i.e., running) energy patterns exists. Mechanical energy recovery of non-bouncing gaits correlates poorly with speed and suggests inefficient use of the inverted pendulum mechanism. Speed ranges of gaits overlap considerably, especially those of grounded running, a gait with CoM mechanics indicative of running but without an aerial phase, and aerial phase running, with no preferential gait at most speeds. Compliant limb morphology and grounded running in birds can be regarded as an evolutionary constraint, but lapwings effectively make use of advantages offered by this gait for a great fraction of their speed range. Thus, effective usage of grounded running during terrestrial locomotion is suggested generally to be a part of striding avian bipedalism-even in species not specialized in walking/running locomotion. PMID:22927254

  7. Observation of variations in the T +T neutron spectrum with varying center-of-mass energy

    NASA Astrophysics Data System (ADS)

    Gatu Johnson, M.; Frenje, J. A.; Zylstra, A.; Petrasso, R. D.; Forrest, C.; Glebov, V. Yu.; Knauer, J. P.; Marshall, F. J.; Michel, T.; Sangster, T. C.; Seka, W.; Shmayda, W.; Stoeckl, C.; Sayre, D.; Caggiano, J. A.; Casey, D. T.; Hatarik, R.; McNabb, D. P.; Pino, J. E.; Bacher, A.; Herrmann, H.; Kim, Y.; Bourgade, J.-. L.; Landoas, O.; Rosse, B.

    2014-10-01

    C. BRUNE, Ohio University - The T +T fusion reaction, which produces two neutrons and an alpha particle in a 3-body final state, has been studied in a series of direct-drive, T2-gas-filled thin (~3 μm) glass-capsule implosions at OMEGA. The shapes of the reaction product spectra are dictated by the final-state interactions between n- α (5He in the ground- and excited states) and n-n (di-neutron interaction). The theory behind final-state interactions is not well understood and detailed study of the reaction product spectra can teach us about the intricacies of the nuclear theory involved. In this presentation, measured neutron spectra are interpreted in terms of the sequential decay through 5He in the ground- and excited states. A clear energy dependence in relative reaction-channel strength at low center-of-mass energy (18-55 keV) is observed in the data. The role of the di-neutron interaction could be more clearly deduced through study of the alpha particle spectrum. In the presentation, we also identify steps required to successfully measure the T +T alpha spectrum in future experiments. This work was supported in part by the U.S. DOE, NLUF, LLNL and LLE.

  8. Charged Higgs searches in ATLAS 13 TeV center of mass pp collision data

    NASA Astrophysics Data System (ADS)

    Griffiths, Justin; Atlas Collaboration

    2016-03-01

    This talk will summarize the search for a charged Higgs that decays to a hadronically decaying tau lepton and its associated neutrino. At high tan β, a Charged Higgs will decay primarily to a t b or τν final state. In such scenarios, the Charged Higgs will be produced in association with a top quark. The final state in this search consists of a hadronically decaying top, at least one b-quark initiated jet, a hadronically decaying tau lepton, and large missing transverse energy from the associated tau neutrinos. The results of Run 1 charged higgs searches at ATLAS will be briefly summarized, including H+ --> c s , t b , W+ Z , and τν . The proton-proton center-of-mass energy increase from Run 1 leads to an increase of the theoretical cross sections by a factor of 4-10, depending on the mass of the charged Higgs. Due to this increase, the run 2 sensitivity is expected to exceed the Run 1 sensitivity with only 3.2 fb-1 of 13 TeV collisions data. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics.

  9. Comparison of three methods to estimate the center of mass during balance assessment.

    PubMed

    Lafond, D; Duarte, M; Prince, F

    2004-09-01

    Evaluation of postural control is generally based on the interpretation of the center of pressure (COP) and the center of mass (COM) time series. The purpose of this study is to compare three methods to estimate the COM which are based on different biomechanical considerations. These methods are: (1) the kinematic method; (2) the zero-point-to-zero-point double integration technique (GLP) and (3) the COP low-pass filter method (LPF). The COP and COM time series have been determined using an experimental setup with a force plate and a 3D kinematic system on six healthy young adult subjects during four different 30 s standing tasks: (a) quiet standing; (b) one leg standing; (c) voluntary oscillation about the ankles and (d) voluntary oscillation about the ankles and hips. To test the difference between the COM trajectories, the root mean square (RMS) differences between each method (three comparisons) were calculated. The RMS differences between kinematic-LPF and GLP-LPF are significantly larger than kinematic-GLP. Our results show that the GLP method is comparable to the kinematic method. Both agree with the unified theory of balance during upright stance. The GLP method is attractive in the clinical perspective because it requires only a force plate to determine the COP-COM variable, which has been demonstrated to have a high reliability. PMID:15275850

  10. Estimating the center of mass of a free-floating body in microgravity.

    PubMed

    Lejeune, L; Casellato, C; Pattyn, N; Neyt, X; Migeotte, P-F

    2013-01-01

    This paper addresses the issue of estimating the position of the center of mass (CoM) of a free-floating object of unknown mass distribution in microgravity using a stereoscopic imaging system. The method presented here is applied to an object of known mass distribution for validation purposes. In the context of a study of 3-dimensional ballistocardiography in microgravity, and the elaboration of a physical model of the cardiovascular adaptation to weightlessness, the hypothesis that the fluid shift towards the head of astronauts induces a significant shift of their CoM needs to be tested. The experiments were conducted during the 57th parabolic flight campaign of the European Space Agency (ESA). At the beginning of the microgravity phase, the object was given an initial translational and rotational velocity. A 3D point cloud corresponding to the object was then generated, to which a motion-based method inspired by rigid body physics was applied. Through simulations, the effects of the centroid-to-CoM distance and the number of frames of the sequence are investigated. In experimental conditions, considering the important residual accelerations of the airplane during the microgravity phases, CoM estimation errors (16 to 76 mm) were consistent with simulations. Overall, our results suggest that the method has a good potential for its later generalization to a free-floating human body in a weightless environment. PMID:24110838

  11. Method of LSD profile asymmetry for estimating the center of mass velocities of pulsating stars

    NASA Astrophysics Data System (ADS)

    Britavskiy, N.; Pancino, E.; Tsymbal, V.; Romano, D.; Cacciari, C.; Clementini, C.

    2016-05-01

    We present radial velocity analysis for 20 solar neighborhood RR Lyrae and 3 Population II Cepheids. High-resolution spectra were observed with either TNG/SARG or VLT/UVES over varying phases. To estimate the center of mass (barycentric) velocities of the program stars, we utilized two independent methods. First, the 'classic' method was employed, which is based on RR Lyrae radial velocity curve templates. Second, we provide the new method that used absorption line profile asymmetry to determine both the pulsation and the barycentric velocities even with a low number of high-resolution spectra and in cases where the phase of the observations is uncertain. This new method is based on a least squares deconvolution (LSD) of the line profiles in order to an- alyze line asymmetry that occurs in the spectra of pulsating stars. By applying this method to our sample stars we attain accurate measurements (+- 2 kms^-1) of the pulsation component of the radial velocity. This results in determination of the barycentric velocity to within 5 kms^-1 even with a low number of high- resolution spectra. A detailed investigation of LSD profile asymmetry shows the variable nature of the project factor at different pulsation phases, which should be taken into account in the detailed spectroscopic analysis of pulsating stars.

  12. Method of LSD profile asymmetry for estimating the center of mass velocities of pulsating stars

    NASA Astrophysics Data System (ADS)

    Britavskiy, Nikolay; Pancino, Elena; Romano, Donatella; Tsymbal, Vadim

    2015-08-01

    We present radial velocity analysis for 20 solar neighborhood RR Lyrae and 3 Population II Cepheids. High-resolution spectra were observed with either TNG/SARG or VLT/UVES over varying phases. To estimate the center of mass (barycentric) velocities of the program stars, we utilized two independent methods. First, the 'classic' method was employed, which is based on RR Lyrae radial velocity curve templates. Second, we provide the new method that used absorption line profile asymmetry to determine both the pulsation and the barycentric velocities even with a low number of high-resolution spectra and in cases where the phase of the observations is uncertain. This new method is based on a Least Squares Deconvolution (LSD) of the line profiles in order to analyze line asymmetry that occurs in the spectra of pulsating stars. By applying this method to our sample stars we attain accurate measurements (± 1 km/s) of the pulsation component of the radial velocity. This results in determination of the barycentric velocity to within 5 km/s even with a low number of high-resolution spectra. A detailed investigation of LSD profile asymmetry shows the variable nature of the project factor at different pulsation phases, which should be taken into account in the detailed spectroscopic analysis of pulsating stars.

  13. Coupled motion of rigid bodies about their center of mass. [Shuttle/payload system

    NASA Technical Reports Server (NTRS)

    Jezewski, D. J.; Donaldson, J. D.

    1979-01-01

    Nontrivial analytical solutions for the coupled motion of two rigid bodies about their center of mass are obtained on the assumptions that the rigid bodies are coupled by a massless rigid boom and that no external forces are acting on the system. Both relative rotational and translational motions of the two bodies are considered. General equations of motion are derived by regarding the two bodies as consisting of two distinct systems of particles and by applying the principle of conservation of angular momentum. It is shown that a basic nontrivial solution can be obtained for the translational problem if an assumption is made concerning the relative orientation of one principal axis of inertia of each body and that fundamental nontrivial solutions are readily obtained for the rotational problem if an additional assumption is made with respect to the symmetry of one body. Certain stability criteria are found for some of these motions by defining regions of constraint for the relative translational and rotational elements.

  14. Lunar highland crustal models based on iron concentrations - Isostasy and center-of-mass displacement

    NASA Technical Reports Server (NTRS)

    Haines, E. L.; Metzger, A. E.

    1980-01-01

    Data is introduced on the iron concentrations of the lunar surface which have been refined by means of convolution corrections to restore the spatial resolution and contrast lost by the omnidirectional spectrometer. This refined iron data is synthesized with other orbital seismic, and lunar sample data to derive highland crustal density and thickness, and isostasy and lunar centers of mass models are examined in light of this new information. A model is developed by which highland crustal density is calculated for each highland region from orbital observations of Fe, Mg and Ti concentrations. The results of this model are presented numerically and graphically for 35 highland and two non-highland regions. Density and thickness results are then applied to two long-standing lunar problems: (1) the nature of highland isostasy, which is shown to be controlled by crustal thickness rather than density, and (2) the separation of the moon's mass and figure centers, which is shown to be due to the crustal thickness difference between the lunar near and far sides.

  15. Center of Mass Estimation for a Spinning Spacecraft Using Doppler Shift of the GPS Carrier Frequency

    NASA Technical Reports Server (NTRS)

    Sedlak, Joseph E.

    2016-01-01

    A sequential filter is presented for estimating the center of mass (CM) of a spinning spacecraft using Doppler shift data from a set of onboard Global Positioning System (GPS) receivers. The advantage of the proposed method is that it is passive and can be run continuously in the background without using commanded thruster firings to excite spacecraft dynamical motion for observability. The NASA Magnetospheric Multiscale (MMS) mission is used as a test case for the CM estimator. The four MMS spacecraft carry star cameras for accurate attitude and spin rate estimation. The angle between the spacecraft nominal spin axis (for MMS this is the geometric body Z-axis) and the major principal axis of inertia is called the coning angle. The transverse components of the estimated rate provide a direct measure of the coning angle. The coning angle has been seen to shift slightly after every orbit and attitude maneuver. This change is attributed to a small asymmetry in the fuel distribution that changes with each burn. This paper shows a correlation between the apparent mass asymmetry deduced from the variations in the coning angle and the CM estimates made using the GPS Doppler data. The consistency between the changes in the coning angle and the CM provides validation of the proposed GPS Doppler method for estimation of the CM on spinning spacecraft.

  16. Behavioral effect of knee joint motion on body's center of mass during human quiet standing.

    PubMed

    Yamamoto, Akio; Sasagawa, Shun; Oba, Naoko; Nakazawa, Kimitaka

    2015-01-01

    The balance control mechanism during upright standing has often been investigated using single- or double-link inverted pendulum models, involving the ankle joint only or both the ankle and hip joints, respectively. Several studies, however, have reported that knee joint motion during quiet standing cannot be ignored. This study aimed to investigate the degree to which knee joint motion contributes to the center of mass (COM) kinematics during quiet standing. Eight healthy adults were asked to stand quietly for 30s on a force platform. Angular displacements and accelerations of the ankle, knee, and hip joints were calculated from kinematic data obtained by a motion capture system. We found that the amplitude of the angular acceleration was smallest in the ankle joint and largest in the hip joint (ankle < knee < hip). These angular accelerations were then substituted into three biomechanical models with or without the knee joint to estimate COM acceleration in the anterior-posterior direction. Although the "without-knee" models greatly overestimated the COM acceleration, the COM acceleration estimated by the "with-knee" model was similar to the actual acceleration obtained from force platform measurement. These results indicate substantial effects of knee joint motion on the COM kinematics during quiet standing. We suggest that investigations based on the multi-joint model, including the knee joint, are required to reveal the physiologically plausible balance control mechanism implemented by the central nervous system. PMID:25248799

  17. Comparison between a center of mass and a foot pressure sensor system for measuring gait parameters in healthy adults

    PubMed Central

    Park, Gunoh; Woo, Youngkeun

    2015-01-01

    [Purpose] The purpose of this study was to determine the relationship between an accelerometer system and a foot pressure sensor system for measuring gait characteristics during walking in healthy adults. [Subjects and Methods] Thirty-five healthy participants with no neurological, musculoskeletal, or cardiopulmonary disorders volunteered for this study. Gait characteristics were measured while participants walked freely along a 10-m walkway using two different measurement systems simultaneously. The first analysis system was based on center of mass using a wireless tri-axial accelerometer and the second system was a foot pressure sensor system. [Results] There was a significant and high correlation between the two systems with respect to gait velocity and cadence. The stride length as a percentage of the stride height measured with the center of mass system was significantly and highly correlated with stride length and stride velocity that was measured with the foot pressure system. Furthermore, stride length from the center of mass system was significantly and highly correlated with stride length and stride velocity from the foot pressure system. [Conclusion] A gait analysis based on a center of mass system is a valid method to assess the effectiveness of therapeutic interventions in a clinical setting. PMID:26644674

  18. Hourglass Fermions

    NASA Astrophysics Data System (ADS)

    Wang, Zhijun; Alexandradinata, A.; Cava, Robert J.; Bernevig, B. Andrei

    Spatial symmetries in crystals are distinguished by whether they preserve the spatial origin. We show how this basic geometric property gives rise to a new topology in band insulators. We study spatial symmetries that translate the origin by a fraction of the lattice period, and find that these nonsymmorphic symmetries protect a novel surface fermion whose dispersion is shaped like an hourglass; surface bands connect one hourglass to the next in an unbreakable zigzag pattern. These exotic fermions are materialized in the large-gap insulators: KHg X (X = As,Sb,Bi), which we propose as the first material class whose topology relies on nonsymmorphic symmetries. Beside the hourglass fermion, a different surface of KHg X manifests a 3D generalization of the quantum spin Hall effect. To describe the bulk topology of nonsymmorphic crystals, we propose a non-Abelian generalization of the geometric theory of polarization. Our nontrivial topology originates not from an inversion of the parity quantum numbers, but rather of the rotational quantum numbers, which we propose as a fruitful in the search for topological materials. Finally, KHg X uniquely exemplifies a cohomological insulator, a concept that we will introduce in a companion work.

  19. Hourglass fermions.

    PubMed

    Wang, Zhijun; Alexandradinata, A; Cava, R J; Bernevig, B Andrei

    2016-04-14

    Spatial symmetries in crystals may be distinguished by whether they preserve the spatial origin. Here we study spatial symmetries that translate the origin by a fraction of the lattice period, and find that these non-symmorphic symmetries protect an exotic surface fermion whose dispersion relation is shaped like an hourglass; surface bands connect one hourglass to the next in an unbreakable zigzag pattern. These 'hourglass' fermions are formed in the large-gap insulators, KHgX (X = As, Sb, Bi), which we propose as the first material class whose band topology relies on non-symmorphic symmetries. Besides the hourglass fermion, another surface of KHgX manifests a three-dimensional generalization of the quantum spin Hall effect, which has previously been observed only in two-dimensional crystals. To describe the bulk topology of non-symmorphic crystals, we propose a non-Abelian generalization of the geometric theory of polarization. Our non-trivial topology originates from an inversion of the rotational quantum numbers, which we propose as a criterion in the search for topological materials. PMID:27075096

  20. Corner height influences center of mass kinematics and path trajectory during turning

    PubMed Central

    Fino, Peter C.; Lockhart, Thurmon E.; Fino, Nora F.

    2014-01-01

    Despite the prevalence of directional changes during every-day gait, relatively little is known about turning compared to straight gait. While the center of mass (COM) movement during straight gait is well characterized, the COM trajectory, and the factors that influence it, are less established for turning. This study investigated the influence of a corner’s height on the COM trajectory as participants walked around the corner. Ten participants (25.3 ± 3.74 years) performed both 90° step and spin turns to the left at self-selected slow, normal, and fast speeds while walking inside a marked path. A pylon was placed on the inside corner of the path. Four different pylon heights were used to correspond to heights of everyday objects: 0 cm (no object), 63 cm (box, crate), 104 cm (desk, table, counter), 167 cm (shelf, cabinet). Obstacle height was found to significantly affect the COM trajectory. Taller obstacles resulted in more distance between the corner and the COM, and between the corner and the COP. Taller obstacles also were associated with greater curvature in the COM trajectory, indicating a smaller turning radius despite the constant 90° corner. Taller obstacles correlated to an increased required coefficient of friction (RCOF) due to the smaller turning radii. Taller obstacles also tended towards greater mediolateral (ML) COM-COP angles, contrary to the initial hypothesis. Additionally, the COM was found to remain outside the base of support (BOS) for the entire first half of stance phase for all conditions indicating a high risk of falls resulting from slips. PMID:25468662

  1. Center of mass velocity-based predictions in balance recovery following pelvis perturbations during human walking.

    PubMed

    Vlutters, M; van Asseldonk, E H F; van der Kooij, H

    2016-05-15

    In many simple walking models, foot placement dictates the center of pressure location and ground reaction force components, whereas humans can modulate these aspects after foot contact. Because of the differences, it is unclear to what extent predictions made by models are valid for human walking. Yet, both model simulations and human experimental data have previously indicated that the center of mass (COM) velocity plays an important role in regulating stable walking. Here, perturbed human walking was studied to determine the relationship of the horizontal COM velocity at heel strike and toe-off with the foot placement location relative to the COM, the forthcoming center of pressure location relative to the COM, and the ground reaction forces. Ten healthy subjects received mediolateral and anteroposterior pelvis perturbations of various magnitudes at toe-off, during 0.63 and 1.25 m s(-1) treadmill walking. At heel strike after the perturbation, recovery from mediolateral perturbations involved mediolateral foot placement adjustments proportional to the mediolateral COM velocity. In contrast, for anteroposterior perturbations, no significant anteroposterior foot placement adjustment occurred at this heel strike. However, in both directions the COM velocity at heel strike related linearly to the center of pressure location at the subsequent toe-off. This relationship was affected by the walking speed and was, for the slow speed, in line with a COM velocity-based control strategy previously applied by others in a linear inverted pendulum model. Finally, changes in gait phase durations suggest that the timing of actions could play an important role during the perturbation recovery. PMID:26994171

  2. Holographic p-wave superconductor models with Weyl corrections

    NASA Astrophysics Data System (ADS)

    Zhang, Lu; Pan, Qiyuan; Jing, Jiliang

    2015-04-01

    We study the effect of the Weyl corrections on the holographic p-wave dual models in the backgrounds of AdS soliton and AdS black hole via a Maxwell complex vector field model by using the numerical and analytical methods. We find that, in the soliton background, the Weyl corrections do not influence the properties of the holographic p-wave insulator/superconductor phase transition, which is different from that of the Yang-Mills theory. However, in the black hole background, we observe that similarly to the Weyl correction effects in the Yang-Mills theory, the higher Weyl corrections make it easier for the p-wave metal/superconductor phase transition to be triggered, which shows that these two p-wave models with Weyl corrections share some similar features for the condensation of the vector operator.

  3. Black Hole Window into p-Wave Dark Matter Annihilation.

    PubMed

    Shelton, Jessie; Shapiro, Stuart L; Fields, Brian D

    2015-12-01

    We present a new method to measure or constrain p-wave-suppressed cross sections for dark matter (DM) annihilations inside the steep density spikes induced by supermassive black holes. We demonstrate that the high DM densities, together with the increased velocity dispersion, within such spikes combine to make thermal p-wave annihilation cross sections potentially visible in γ-ray observations of the Galactic center (GC). The resulting DM signal is a bright central point source with emission originating from DM annihilations in the absence of a detectable spatially extended signal from the halo. We define two simple reference theories of DM with a thermal p-wave annihilation cross section and establish new limits on the combined particle and astrophysical parameter space of these models, demonstrating that Fermi Large Area Telescope is currently sensitive to thermal p-wave DM over a wide range of possible scenarios for the DM distribution in the GC. PMID:26684108

  4. Black Hole Window into p -Wave Dark Matter Annihilation

    NASA Astrophysics Data System (ADS)

    Shelton, Jessie; Shapiro, Stuart L.; Fields, Brian D.

    2015-12-01

    We present a new method to measure or constrain p -wave-suppressed cross sections for dark matter (DM) annihilations inside the steep density spikes induced by supermassive black holes. We demonstrate that the high DM densities, together with the increased velocity dispersion, within such spikes combine to make thermal p -wave annihilation cross sections potentially visible in γ -ray observations of the Galactic center (GC). The resulting DM signal is a bright central point source with emission originating from DM annihilations in the absence of a detectable spatially extended signal from the halo. We define two simple reference theories of DM with a thermal p -wave annihilation cross section and establish new limits on the combined particle and astrophysical parameter space of these models, demonstrating that Fermi Large Area Telescope is currently sensitive to thermal p -wave DM over a wide range of possible scenarios for the DM distribution in the GC.

  5. P-wave dispersion: What we know till now?

    PubMed Central

    Aytemir, Kudret; Oto, Ali

    2016-01-01

    P-wave dispersion is defined as the difference between the maximum and the minimum P-wave duration recorded from multiple different-surface ECG leads. It has been known that increased P-wave duration and P-wave dispersion reflect prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses, which are well-known electrophysiologic characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation. Extensive clinical evaluation of P-wave dispersion has been performed in the assessment of the risk for atrial fibrillation in patients without apparent heart disease, in hypertensives, in patients with coronary artery disease, in patients undergoing coronary artery bypass surgery, in patients with congenital heart diseases, as well as in other groups of patients suffering from various cardiac or non-cardiac diseases. In this paper, we aimed to summarize the measurement methods, current use in different clinical situations, strengths and limitations of the of P-wave dispersion. PMID:27081484

  6. Ray-theoretical modeling of secondary microseism P-waves

    NASA Astrophysics Data System (ADS)

    Farra, V.; Stutzmann, E.; Gualtieri, L.; Schimmel, M.; Ardhuin, F.

    2016-06-01

    Secondary microseism sources are pressure fluctuations close to the ocean surface. They generate acoustic P-waves that propagate in water down to the ocean bottom where they are partly reflected, and partly transmitted into the crust to continue their propagation through the Earth. We present the theory for computing the displacement power spectral density of secondary microseism P-waves recorded by receivers in the far field. In the frequency domain, the P-wave displacement can be modeled as the product of (1) the pressure source, (2) the source site effect that accounts for the constructive interference of multiply reflected P-waves in the ocean, (3) the propagation from the ocean bottom to the stations, (4) the receiver site effect. Secondary microseism P-waves have weak amplitudes, but they can be investigated by beamforming analysis. We validate our approach by analyzing the seismic signals generated by Typhoon Ioke (2006) and recorded by the Southern California Seismic Network. Back projecting the beam onto the ocean surface enables to follow the source motion. The observed beam centroid is in the vicinity of the pressure source derived from the ocean wave model WAVEWATCH IIIR. The pressure source is then used for modeling the beam and a good agreement is obtained between measured and modeled beam amplitude variation over time. This modeling approach can be used to invert P-wave noise data and retrieve the source intensity and lateral extent.

  7. Ray-theoretical modeling of secondary microseism P waves

    NASA Astrophysics Data System (ADS)

    Farra, V.; Stutzmann, E.; Gualtieri, L.; Schimmel, M.; Ardhuin, F.

    2016-09-01

    Secondary microseism sources are pressure fluctuations close to the ocean surface. They generate acoustic P waves that propagate in water down to the ocean bottom where they are partly reflected and partly transmitted into the crust to continue their propagation through the Earth. We present the theory for computing the displacement power spectral density of secondary microseism P waves recorded by receivers in the far field. In the frequency domain, the P-wave displacement can be modeled as the product of (1) the pressure source, (2) the source site effect that accounts for the constructive interference of multiply reflected P waves in the ocean, (3) the propagation from the ocean bottom to the stations and (4) the receiver site effect. Secondary microseism P waves have weak amplitudes, but they can be investigated by beamforming analysis. We validate our approach by analysing the seismic signals generated by typhoon Ioke (2006) and recorded by the Southern California Seismic Network. Backprojecting the beam onto the ocean surface enables to follow the source motion. The observed beam centroid is in the vicinity of the pressure source derived from the ocean wave model WAVEWATCH IIIR. The pressure source is then used for modeling the beam and a good agreement is obtained between measured and modeled beam amplitude variation over time. This modeling approach can be used to invert P-wave noise data and retrieve the source intensity and lateral extent.

  8. Rotary and radial forcing effects on center-of-mass locomotion dynamics.

    PubMed

    Shen, Z H; Larson, P L; Seipel, J E

    2014-09-01

    Rotary and radial forcing are two common actuation methods for legged robots. However, these two orthogonal methods of center-of-mass (CoM) forcing have not been compared as potentially alternative strategies of actuation. In this paper, we compare the CoM stability and energetics of running with rotary and radial actuation through the simulation of two models: the rotary-forced spring-loaded inverted pendulum (rotary-forced-SLIP), and the radially-forced-SLIP. We model both radial and rotary actuation in the simplest way, applying them as a constant force during the stance portion of the gait. A simple application of constant rotary forcing throughout stance is capable of producing fully-asymptotically stable motion; however, a similarly constant application of radial forcing throughout the stance is not capable of producing stable solutions. We then allow both the applied rotary and radial forcing functions to turn on or off based on the occurrence of the mid-stance event, which breaks the symmetry of actuation during stance towards a net forward propulsion. We find that both a rotary force applied in the first half of stance and a radial force applied in the second half of stance, are capable of stabilizing running. Interestingly, these two forcing methods improve the motion stability in different ways. Rotary forcing first reduces then greatly increases the size of the stable parameter region when gradually increased. Radial forcing expands the stable parameter region, but only in a moderate way. Also, it is found that parameter region stabilized by rotary and radial forcing are largely complementary. Overall, rotary forcing can better stabilize running for both constant and event-based forcing functions that were attempted. This indicates that rotary forcing has an inherent capability of stabilizing running, even when minimal time-or-event-or-state feedback is present. Radial forcing, however, tends to be more energy efficient when compared to rotary forcing

  9. Prediction of landslide run-out distance based on slope stability analysis and center of mass approach

    NASA Astrophysics Data System (ADS)

    Firmansyah; Feranie, S.; Tohari, Adrin; Latief, F. D. E.

    2016-01-01

    Mitigation of landslide hazard requires the knowledge of landslide run-out distance. This paper presents the application of slope stability analysis and center of mass approach to predict the run-out distance of a rotational landslide model with different soil types. The Morgenstern-Price method was used to estimate the potential sliding zone and volume of landslide material. The center of mass approach used a simple Coulomb friction model to determine the run-out distance. Results of the slope stability analysis showed that the soil unit weight can influence the depth of sliding zone, and the volume of unstable material. The slope model of silty sand and gravel would have the largest volume of unstable mass. From the Coulomb friction analysis, this slope model has higher run-out distance and velocity than other slope models. Thus, the run-out distance will be influenced by soil type and the dimension of unstable soil mass.

  10. Linear center-of-mass dynamics emerge from non-linear leg-spring properties in human hopping.

    PubMed

    Riese, Sebastian; Seyfarth, Andre; Grimmer, Sten

    2013-09-01

    Given the almost linear relationship between ground-reaction force and leg length, bouncy gaits are commonly described using spring-mass models with constant leg-spring parameters. In biological systems, however, spring-like properties of limbs may change over time. Therefore, it was investigated how much variation of leg-spring parameters is present during vertical human hopping. In order to do so, rest-length and stiffness profiles were estimated from ground-reaction forces and center-of-mass dynamics measured in human hopping. Trials included five hopping frequencies ranging from 1.2 to 3.6 Hz. Results show that, even though stiffness and rest length vary during stance, for most frequencies the center-of-mass dynamics still resemble those of a linear spring-mass hopper. Rest-length and stiffness profiles differ for slow and fast hopping. Furthermore, at 1.2 Hz two distinct control schemes were observed. PMID:23880438

  11. Instabilities in fermions and BEC mixtures

    NASA Astrophysics Data System (ADS)

    Tsai, Shan-Wen; Kalas, Ryan M.; Timmermans, Eddy

    2010-03-01

    We study instabilities in a mixture of interacting fermionic and bosonic ultra-cold atoms. We focus on BCS transitions of the fermions that can be generated from attractive interactions mediated by bosons that are in a BEC phase. We study the p-wave instability [1] for indistinguishable (single spin) fermions in detail, taking into account the dynamical part of the mediated interaction. We employ a functional renormalization-group approach that takes retardation effects into account [2], calculate the renormalized interaction vertices and self-energies for this system, and obtain the phase diagram, sub-dominant instabilities, and transition temperatures, giving estimates for realistic parameters. We also investigate what happens in this system close to the phase-separation transition [3], and explore other possible fermionic phases, including fermion BCS pairings with other pairing symmetries. [4pt] [1] D. V. Efremov and L. Viverit, Phys. Rev. B 65, 134519 (2002)[0pt] [2] S.-W. Tsai et al., Phys. Rev. B 72, 054531 (2005)[0pt] [3] D. H. Santamore and E. Timmermans, Phys. Rev. A 78, 013619 (2008)

  12. Radiation Pressure Forces, the Anomalous Acceleration, and Center of Mass Motion for the TOPEX/POSEIDON Spacecraft

    NASA Technical Reports Server (NTRS)

    Kubitschek, Daniel G.; Born, George H.

    2000-01-01

    Shortly after launch of the TOPEX/POSEIDON (T/P) spacecraft (s/c), the Precision Orbit Determination (POD) Team at NASA's Goddard Space Flight Center (GSFC) and the Center for Space Research at the University of Texas, discovered residual along-track accelerations, which were unexpected. Here, we describe the analysis of radiation pressure forces acting on the T/P s/c for the purpose of understanding and providing an explanation for the anomalous accelerations. The radiation forces acting on the T/P solar army, which experiences warping due to temperature gradients between the front and back surfaces, are analyzed and the resulting along-track accelerations are determined. Characteristics similar to those of the anomalous acceleration are seen. This analysis led to the development of a new radiation form model, which includes solar array warping and a solar array deployment deflection of as large as 2 deg. As a result of this new model estimates of the empirical along-track acceleration are reduced in magnitude when compared to the GSFC tuned macromodel and are less dependent upon beta(prime), the location of the Sun relative to the orbit plane. If these results we believed to reflect the actual orientation of the T/P solar array then motion of the solar array must influence the location of the s/c center of mass. Preliminary estimates indicate that the center of mass can vary by as much as 3 cm in the radial component of the s/c's position due to rotation of the deflected, warped solar array panel .The altimeter measurements rely upon accurate knowledge of the center of mass location relative to the s/c frame of reference. Any radial motion of the center of mass directly affects the altimeter measurements.

  13. Center-of-mass corrections for sub-cm-precision laser-ranging targets: Starlette, Stella and LARES

    NASA Astrophysics Data System (ADS)

    Otsubo, Toshimichi; Sherwood, Robert A.; Appleby, Graham M.; Neubert, Reinhart

    2015-04-01

    To realize the full potential of satellite laser ranging for accurate geodesy, it is crucial that all systematic effects in the measurements are taken into account. This paper derives new values for the so-called center-of-mass corrections for three geodetic satellites that are regularly tracked and used in geodetic studies. Optical responses of the twin satellites, Starlette and Stella, and the LARES satellite are retrieved from kHz single-photon laser-ranging data observed at Herstmonceux and Potsdam. The detection timing inside single-photon systems, C-SPAD-based systems and photomultiplier-based systems is numerically simulated, and the center-of-mass corrections are derived to be in the range of 74 to 82 mm for Starlette and Stella, and 127-135 mm for LARES. The system dependence is below 1 cm, but should not be ignored for millimeter accuracy. The longtime standard center-of-mass correction 75 mm of Starlette and Stella is revealed to be too small for the current laser-ranging stations on average, which is considered to have resulted in a non-negligible systematic error in geodetic products.

  14. Detection of the electrocardiogram P-wave using wavelet analysis

    NASA Astrophysics Data System (ADS)

    Anant, Kanwaldip S.; Dowla, Farid U.; Rodrigue, Garry H.

    1994-03-01

    Since wavelet analysis is an effective tool for analyzing transient signals, we studied its feature extraction and representation properties for events in electrocardiogram (EKG) data. Significant features of the EKG include the P-wave, the QRS complex, and the T-wave. For this paper the feature that we chose to focus on was the P-wave. Wavelet analysis was used as a preprocessor for a backpropagation neural network with conjugate gradient learning. The inputs to the neural network were the wavelet transforms of EKGs at a particular scale. The desired output was the location of the P-wave. The results were compared to results obtained without using the wavelet transform as a preprocessor.

  15. Detection of the electrocardiogram P-wave using wavelet analysis

    SciTech Connect

    Anant, K.S.; Rodrigue, G.H. |; Dowla, F.U.

    1994-01-01

    Since wavelet analysis is an effective tool for analyzing transient signals, we studied its feature extraction and representation properties for events in electrocardiogram (EKG) data. Significant features of the EKG include the P-wave, the QRS complex, and the T-wave. For this paper the feature that we chose to focus on was the P-wave. Wavelet analysis was used as a pre-processor for a backpropagation neural network with conjugate gradient learning. The inputs to the neural network were the wavelet transforms of EKGs at a particular scale. The desired output was the location of the P-wave. The results were compared to results obtained without using the wavelet transform as a pre-processor.

  16. Supercurrent in a p-wave holographic superconductor

    SciTech Connect

    Zeng Huabi; Sun Weimin; Zong Hongshi

    2011-02-15

    The p-wave and p+ip-wave holographic superconductors with fixed DC supercurrent are studied by introducing a nonvanishing vector potential. We find that close to the critical temperature T{sub c} of zero current, the numerical results of both the p-wave model and the p+ip model are the same as those of Ginzburg-Landau (GL) theory; for example, the critical current is j{sub c}{approx}(T{sub c}-T){sup 3/2} and the phase transition in the presence of a DC current is a first-order transition. Beside the similar results between both models, the p+ip superconductor shows isotropic behavior for the supercurrent, while the p-wave superconductor shows anisotropic behavior for the supercurrent.

  17. Manipulation of p-wave scattering of cold atoms in low dimensions using the magnetic field vector

    NASA Astrophysics Data System (ADS)

    Peng, Shi-Guo; Tan, Shina; Jiang, Kaijun

    2014-03-01

    It is well known that the magnetic Feshbach resonances of cold atoms are sensitive to the magnitude of the external magnetic field. Much less attention has been paid to the direction of such a field. In this work we calculate the scattering properties of spin polarized fermionic atoms in reduced dimensions, near a p-wave Feshbach resonance. Because of spatial anisotropy of the p-wave interaction, the scattering has nontrivial dependence on both the magnitude and the direction of the magnetic field. In addition, we identify an inelastic scattering process which is impossible in the isotropic-interaction model; the rate of this process depends considerably on the direction of the magnetic field. Significantly, an EPR entangled pair of identical fermions may be produced during this inelastic collision. This work opens a new method to manipulate resonant cold atomic interactions. CPSF (Grant No. 2012M510187), Special Financial Grant from CPSF (Grant No. 2013T60762), the NSFC projects (Grant No. 11004224 and No.11204355) and the NFRP- China (Grant No. 2011CB921601), NSF (Grant No. PHY-1068511), Alfred P. Sloan Foundation

  18. Laboratory monitoring of P-waves in partially saturated sand

    NASA Astrophysics Data System (ADS)

    Barrière, J.; Bordes, C.; Brito, D.; Sénéchal, P.; Perroud, H.

    2011-12-01

    Seismic data depends on a variety of hydrogeological properties of the prospected porous media such as porosity, permeability and fluid saturation. We have performed a laboratory experiment in the kiloHertz range in order to analyze the role of partial saturation on direct propagating P-waves phase velocity and attenuation. The experiment consists of a sand-filled tank 107 cm x 34 cm x 35cm equipped with accelerometers and water capacitance probes. The P-waves seismic propagation is generated by hitting a steel ball on a granite plate on the one lateral side of the container. Several imbibition/drainage cycles are performed between the water residual saturation and the gas residual saturation. The laboratory seismic data are processed by two Continuous Wavelet Transforms using one real mother wavelet (Mexican hat) and one complex (Morlet) to recover velocity and attenuation as a function of frequency. Phase velocity of direct P-wave decreases with an increase of water content and is quite consistent with the low frequency limit of the Biot's theory both for imbibition and drainage. The interpretation of the P-waves attenuation needs to go beyond the macroscopic fluid flow of Biot's theory and to introduce a viscoelastic contribution linked to the grain to grain overall losses which are described by a constant Q-model. A strong hysteresis between imbibition and drainage is observed and explained by introducing an effective permeability depending on water and gas relative permeabilities (Van Genuchten model).

  19. Uppermost mantle P wave velocities beneath Turkey and Iran

    SciTech Connect

    Chen, C.; Chen, W.; Molnar, P.

    1980-01-01

    The uppermost mantle P wave velocities beneath Turkey and Iran were estimated by applying the conventional travel time-distance relation method to arrival times of well located earthquakes recorded at a few stations. The average uppermost mantle P wave velocity under Turkey is estimated from two stations of the World Wide Standardized Seismograph Network (WWSSN), Istanbul and Tabriz. The data are consistent with a crust of uniform, but poorly determined, thickness and an uppermost mantle P wave velocity of 7.73 +- 0.08 km/s. This velocity is very similar to that for the Aegean Sea and suggests that its structure could be closely related to that beneath Turkey. For Iran, the results calculated from travel times to three WWSSN stations, Meshed, Shiraz, and Tabriz, can be explained by a crust dipping toward the south-southeast at about 1/sup 0/ with an uppermost mantle P wave velocity of 8.0 +- 0.1 km/s. If the crustal thickness were 34 km in the north it would reach about 49 km in the south. Based on these uppermost mantle velocities, the temperature at Moho beneath Turkey is probably close to the melting temperature of peridotite but that beneath Iran is probably lower.

  20. Surface Sediment Effects on Teleseismic P Wave Ground Displacement

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Nolet, G.; Dahlen, F. A.

    2001-12-01

    Large scatter in short-period body-wave amplitude measurements over short distances have been widely observed. "Station corrections" are essential when amplitude data are applied to determine event magnitude, and, occasionally, to explore deeper subsurface structures. In this paper, we investigated the effects of surface sediments on teleseismic P wave displacement amplitude assuming layered crust structures. Local scattering effects are ignored since we are interested in the teleseismic waves with dominant frequency well below 1 Hz. Generally, displacements are amplified as seismic waves propagate into a low-impedance sediment layer. As the wavefield interacts with a surface sediment layer, P wave reverberations de-amplify the ground displacement recorded by seismic sensors at the surface. The de-amplification effect is dependent on the period of the seismic wave. Numerical calculations show when the period of the seismic wave is much longer than P wave 2-way travel time in the surface sediment layer, it doesn't "feel" the existance of the sediment layer, which leaves amplitudes intact except for about a factor of 2 amplification effect caused by the free-surface. At shorter period, the amplification effect is approximately linearly-dependent on the period of seismic waves. When the period of seismic wave is short and within a couple of times of the P wave 2-way travel time in the sediment, the amplification effects varies greatly over a small range of seismic wave period. It indicates that surface displacement amplitude of high-frequency P wave could vary laterally up to an order of magnitude where P wave velocity in the surface weathering layer is low (less than few hundred meters per second) and lateral variations of the relative impedance are extremely large. A 7-layer 2x2 degree global crust model, {Crust2.0} (Laske et al) is used to estimate frequency-dependent station corrections in the continents and the stable period range of teleseismic P waves for

  1. Impact of the equivalent center of mass separating from the sliding surface on the isolation performance of friction pendulum bearings

    NASA Astrophysics Data System (ADS)

    Xia, Junyong; Ning, Xiangliang; Tan, Ping; Hao, Hongxiao; Chen, Guoping

    2015-12-01

    A new equivalent center of mass model of FPBs (friction pendulum bearings) is introduced, and based on this model, coefficient j of the equivalent center of mass separating from the sliding surface is defined. It is thought in theory that j has a significant impact on the isolation parameter of FPBs, since the equivalent post-yielding stiffness and friction coefficients are not simply determined by sliding radius and sliding friction pairs. The results of numerical simulation analysis using ABAQUS conducted on two groups of FPBs support this viewpoint. For FPBs with the same sliding radius and sliding friction pairs, the FPB modules of structural analysis software such as ETABS could only distinguish the equivalent transformation using j one by one. The seismic response data obtained in a base isolation calculation example of FPBs are very different, which reveals that j's impact on the isolation effectiveness of FPBs cannot be ignored. The introduction of j will help improve the classical structural theory of FPBs and the weak points of structural analysis software based on this theory, which is important in achieving more accurate analyses in structural design.

  2. Q^2 Dependence of the S_{11}(1535) Photocoupling and Evidence for a P-wave resonance in eta electroproduction

    SciTech Connect

    Haluk Denizli; James Mueller; Steven Dytman; M.L. Leber; R.D. Levine; J. Miles; Kui Kim; Gary Adams; Moscov Amaryan; Pawel Ambrozewicz; Marco Anghinolfi; Burin Asavapibhop; G. Asryan; Harutyun Avakian; Hovhannes Baghdasaryan; Nathan Baillie; Jacques Ball; Nathan Baltzell; Steve Barrow; V. Batourine; Marco Battaglieri; Kevin Beard; Ivan Bedlinski; Ivan Bedlinskiy; Mehmet Bektasoglu; Matthew Bellis; Nawal Benmouna; Nicola Bianchi; Angela Biselli; Billy Bonner; Sylvain Bouchigny; Sergey Boyarinov; Robert Bradford; Derek Branford; William Briscoe; William Brooks; Stephen Bueltmann; Volker Burkert; Cornel Butuceanu; John Calarco; Sharon Careccia; Daniel Carman; Catalina Cetina; Shifeng Chen; Philip Cole; Alan Coleman; Patrick Collins; Philip Coltharp; Dieter Cords; Pietro Corvisiero; Donald Crabb; Volker Crede; John Cummings; Natalya Dashyan; Raffaella De Vita; Enzo De Sanctis; Pavel Degtiarenko; Lawrence Dennis; Alexandre Deur; Kalvir Dhuga; Richard Dickson; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; P. Dragovitsch; Michael Dugger; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; Lamiaa Elfassi; Latifa Elouadrhiri; A. Empl; Paul Eugenio; Laurent Farhi; Renee Fatemi; Gleb Fedotov; Gerald Feldman; Robert Feuerbach; Tony Forest; Valera Frolov; Herbert Funsten; Sally Gaff; Michel Garcon; Gagik Gavalian; Gerard Gilfoyle; Kevin Giovanetti; Pascal Girard; Francois-Xavier Girod; John Goetz; Atilla Gonenc; Ralf Gothe; Keith Griffioen; Michel Guidal; Matthieu Guillo; Nevzat Guler; Lei Guo; Vardan Gyurjyan; Kawtar Hafidi; Hayk Hakobyan; Rafael Hakobyan; John Hardie; David Heddle; F. Hersman; Kenneth Hicks; Ishaq Hleiqawi; Maurik Holtrop; Jingliang Hu; Charles Hyde; Charles Hyde-Wright; Yordanka Ilieva; David Ireland; Boris Ishkhanov; Eugeny Isupov; Mark Ito; David Jenkins; Hyon-Suk Jo; Kyungseon Joo; Henry Juengst; Narbe Kalantarians; J.H. Kelley; James Kellie; Mahbubul Khandaker; K. Kim; Wooyoung Kim; Andreas Klein; Franz Klein; Mike Klusman; Mikhail Kossov; Laird Kramer; V. Kubarovsky; Joachim Kuhn; Sebastian Kuhn; Sergey Kuleshov; Jeff Lachniet; Jean Laget; Jorn Langheinrich; David Lawrence; Kenneth Livingston; Haiyun Lu; K. Lukashin; Marion MacCormick; Joseph Manak; Nikolai Markov; Simeon McAleer; Bryan McKinnon; John McNabb; Bernhard Mecking; Mac Mestayer; Curtis Meyer; Tsutomu Mibe; Konstantin Mikhaylov; Ralph Minehart; Marco Mirazita; Rory Miskimen; Viktor Mokeev; Kei Moriya; Steven Morrow; M. Moteabbed; Valeria Muccifora; Gordon Mutchler; Pawel Nadel-Turonski; James Napolitano; Rakhsha Nasseripour; Steve Nelson; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Grant O'Rielly; Mikhail Osipenko; Alexander Ostrovidov; Kijun Park; Evgueni Pasyuk; Craig Paterson; Gerald Peterson; Sasha Philips; Joshua Pierce; Nikolay Pivnyuk; Dinko Pocanic; Oleg Pogorelko; Ermanno Polli; S. Pozdniakov; Barry Preedom; John Price; Yelena Prok; Dan Protopopescu; Liming Qin; Brian Raue; Gregory Riccardi; Giovanni Ricco; Marco Ripani; Barry Ritchie; Federico Ronchetti; Guenther Rosner; Patrizia Rossi; David Rowntree; Philip Rubin; Franck Sabatie; Konstantin Sabourov; Julian Salamanca; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Aziz Shafi; Youri Sharabian; Jeremiah Shaw; Nikolay Shvedunov; Sebastio Simionatto; Alexander Skabelin; Elton Smith; Lee Smith; Daniel Sober; Daria Sokhan; M. Spraker; Aleksey Stavinskiy; Samuel Stepanyan; Stepan Stepanyan; Burnham Stokes; Paul Stoler; I.I. Strakovsky; Steffen Strauch; Mauro Taiuti; Simon Taylor; David Tedeschi; Ulrike Thoma; R. Thompson; Avtandil Tkabladze; Svyatoslav Tkachenko; Clarisse Tur; Maurizio Ungaro; Michael Vineyard; Alexander Vlassov; Kebin Wang; Daniel Watts; Lawrence Weinstein; Henry Weller; Dennis Weygand; M. Williams; Elliott Wolin; Michael Wood; Amrit Yegneswaran; Junho Yun; Lorenzo Zana; Jixie Zhang; Bo Zhao; Zhiwen Zhao

    2007-07-01

    New cross sections for the reaction $ep \\to e'\\eta p$ are reported for total center of mass energy $W$=1.5--2.3 GeV and invariant squared momentum transfer $Q^2$=0.13--3.3 GeV$^2$. This large kinematic range allows extraction of new information about response functions, photocouplings, and $\\eta N$ coupling strengths of baryon resonances. A sharp structure is seen at $W\\sim$ 1.7 GeV. The shape of the differential cross section is indicative of the presence of a $P$-wave resonance that persists to high $Q^2$. Improved values are derived for the photon coupling amplitude for the $S_{11}$(1535) resonance. The new data greatly expands the $Q^2$ range covered and an interpretation of all data with a consistent parameterization is provided.

  3. Fermionization and Hubbard models

    NASA Astrophysics Data System (ADS)

    Dargis, P.; Maassarani, Z.

    1998-12-01

    We introduce a transformation which allows the fermionization of operators of any one-dimensional spin-chain. This fermionization procedure is independent of any eventual integrable structure and is compatible with it. We illustrate this method on various integrable and non-integrable chains, and deduce some general results. In particular, we fermionize XXC spin-chains and study their symmetries. Fermionic realizations of certain Lie algebras and superalgebras appear naturally as symmetries of some models. We also fermionize recently obtained Hubbard models, and obtain for the first time multispecies analogues of the Hubbard model, in their fermionic form. We comment on the conflict between symmetry enhancement and integrability of these models. Finally, the fermionic versions of the non-integrable spin-1 and spin- {3}/{2} Heisenberg chains are obtained.

  4. Lateral oscillations of the center of mass of bipeds as they walk. Inverted pendulum model with two degrees of freedom

    NASA Astrophysics Data System (ADS)

    H Goldsztein, Guillermo

    2015-10-01

    The use of inverted pendulum models to study the bio-mechanics of biped walkers is a common practice. In its simplest form, the inverted pendulum consists of a point mass, which models the center of mass of the biped, attached to two straight mass-less legs. Most works using the simplest inverted pendulum model constrain the mass and the legs to the sagittal plane (the plane that contains the direction perpendicular to the ground and the direction toward the biped is walking). In this article, we remove this constrain and use this unconstrained inverted pendulum model to study the oscillations the mass experiences in the direction perpendicular to the sagittal plane as the biped walks. While small, these oscillations are unavoidable and of importance in the understanding of balance and stability of walkers, as well as walkers induced oscillations in pedestrian bridges.

  5. Statistical and evaporation models for the neutron emission energy spectrum in the center-of-mass system from fission fragments

    NASA Astrophysics Data System (ADS)

    Kawano, T.; Talou, P.; Stetcu, I.; Chadwick, M. B.

    2013-09-01

    The neutron emission energy spectra in the CMS (center-of-mass) frame from two compound nuclei produced by fission are studied. The neutron spectra calculated with the Hauser-Feshbach statistical model are compared with the evaporation theory, and the definition of the temperature is revisited. Using the Monte Carlo technique we average the CMS neutron spectra from many fission fragments to construct the representative CMS spectrum from both the light and heavy fragments. The CMS spectra for each fission fragment pair are also converted into the laboratory frame to calculate the total prompt fission neutron spectrum that can be observed experimentally. This is compared to measured laboratory data for thermal neutron induced fission on 235U. We show that the Hauser-Feshbach calculation gives a different spectrum shape than the Madland-Nix model calculation.

  6. The One-Body and Two-Body Density Matrices of Finite Nuclei and Center-of-Mass Correlations

    SciTech Connect

    Shebeko, A.; Papakonstantinou, P.; Mavrommatis, E.

    2006-04-26

    A method is presented for the calculation of the one-body (1DM) and two-body (2DM) density matrices and their Fourier transforms in momentum space, that is consistent with the requirement for translational invariance (TI), in the case of a nucleus (a finite self-bound system). We restore TI by using the so-called fixed center-of-mass (CM) approximation for constructing an intrinsic nuclear ground state wavefunction (WF) by starting from a non-translationally invariant (nTI) WF and applying a projection prescription. We discuss results for the one-body (OBMD) and two-body (TBMD) momentum distributions of the 4He nucleus calculated with the Slater determinant of the harmonic oscillator (HO) orbitals, as the initial nTI WF. Effects of such an inclusion of CM correlations are found to be quite important in the momentum distributions.

  7. Tests of models for parton fragmentation in e e annihilation. [29 GeV center-of-mass energy

    SciTech Connect

    Gary, J.W.

    1985-11-01

    We examine the distribution of particles in the three jet events of e e annihilation. The data was collected with the PEP-4/Time Projection Chamber detector at 29 GeV center-of-mass energy at PEP. The experimental distributions are compared to the predictions of several fragmentation models which describe the transition of quarks and gluons into hadrons. In particular, our study emphasizes the three fragmentation models which are currently in widest use: the Lund string model, the Webber cluster model and the independent fragmentation model. These three models each possess different Lorentz frame structures for the distribution of hadron sources relative to the overall event c.m. in three jet events. The Lund string and independent fragmentation models are tuned to describe global event properties of our multihadronic annihilation event sample. This tuned Lund string model provides a good description of the distribution of particles between jet axes in three jet events, while the independent fragmentation model does not. We verify that the failure of the independent fragmentation model is not a consequence of parameter tuning or of model variant. The Webber cluster model, which is untuned, does not describe the absolute particle densities between jets but correctly predicts the ratios of those densities, which are less sensitive to the tuning. These results provide evidence that the sources of hadrons are boosted with respect to the overall center-of-mass in three jet events, with components of motion normal to the jet axes. The distribution of particles close to jet axes provides additional support for this conclusion. 94 refs.

  8. Endstates in multichannel spinless p-wave superconducting wires

    NASA Astrophysics Data System (ADS)

    Rieder, M.-T.; Kells, G.; Duckheim, M.; Meidan, D.; Brouwer, P. W.

    2012-09-01

    Multimode spinless p-wave superconducting wires with a width W much smaller than the superconducting coherence length ξ are known to have multiple low-energy subgap states localized near the wire's ends. Here we compare the typical energies of such endstates for various terminations of the wire: A superconducting wire coupled to a normal-metal stub, a weakly disordered superconductor wire and a wire with smooth confinement. Depending on the termination, we find that the energies of the subgap states can be higher or lower than for the case of a rectangular wire with hard-wall boundaries.

  9. Impact of Phase Transitions on P Wave Velocities

    SciTech Connect

    D Weidner; L Li

    2011-12-31

    In regions where a high pressure phase is in equilibrium with a low pressure phase, the bulk modulus defined by the P-V relationship is greatly reduced. Here we evaluate the effect of such transitions on the P wave velocity. A model, where cation diffusion is the rate limiting factor, is used to project laboratory data to the conditions of a seismic wave propagating in the two-phase region. We demonstrate that for the minimum expected effect there is a significant reduction of the seismic velocity, as large as 10% over a narrow depth range.

  10. P-wave contacts for two dimensional quatum gas

    NASA Astrophysics Data System (ADS)

    Zhang, Yicai; Yu, Zhenhua; Zhang, Shizhong

    The s-wave contact has played an important role in our understanding of the strongly interacting Fermi gases. Recently, theoretical and experimental work has shown that two similar contacts exist for a p-wave interacting Fermi gas in three-dimensions. In this work, we extend the considerations to two dimensional spineless Fermi gas and derive exact results regarding the energy, momentum distributions and in particular, shifts of monopole frequency in a harmonic trap. Asymptotic formula for the frequency shift is given at high temperature via virial expansion and this can be checked by future experiments.

  11. Anomalous delays of teleseismic P waves in Yellowstone National Park

    USGS Publications Warehouse

    Iyer, H.M.

    1975-01-01

    TELESEISMIC P waves recorded by a short-period seismic network, comprising 12 stations, in Yellowstone National Park, show anomalous delays of 1-2 s in their travel times in the central region of the park relative to the surrounding area. To explain this phenomenon, I propose that a substantial body of low velocity material is present beneath the park, with horizontal dimensions of several tens of kilometres; it may be the magma chamber associated with the volcanism of Yellowstone (ref. 1, and G. P. Eaton et al., unpublished). ?? 1975 Nature Publishing Group.

  12. Skyrmion Flux Lattices in p,-wave Superconductors

    NASA Astrophysics Data System (ADS)

    Li, Qi; Toner, John; Belitz, Dietrich

    2007-03-01

    In p,-wave superconductors, topological excitations known as skyrmions are allowed, in addition to the usual vortices. In strongly type-II materials in an external magnetic field, a skyrmion flux lattice is expected to be energetically favored compared to a vortex flux lattice [1]. We analytically calculate the energy, magnetization curves (B(H)), and elasticity of skyrmion flux lattices in p,-wave superconductors near the lower critical field Hc1, and use these results with the Lindemann criterion to predict their melting curve [2]. In striking contrast to vortex flux lattices, which always melt at an external field H > Hc1, skyrmion flux lattices never melt near Hc1. This provides a simple and unambiguous test for the presence of skyrmions. In addition, the internal magnetic field distributions (which are measurable by muon spin rotation techniques [3]) of skyrmion and vortex lattices are very different. [1] A. Knigavko, B. Rosenstein, and Y.F. Chen, Phys. Rev. B 60, 550 (1999). [2] Qi Li, John Toner, and D. Belitz, cond-mat/0607391 [3] J.E. Sonier, J. Phys. Cond. Matt. 16, S4499 (2004)

  13. P-wave velocity structure beneath the northern Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Park, Y.; Kim, K.; Jin, Y.

    2010-12-01

    We have imaged tomographically the tree-dimensional velocity structure of the upper mantle beneath the northern Antarctic Peninsula using teleseismic P waves. The data came from the seven land stations of the Seismic Experiment in Patagonia and Antarctica (SEPA) campaigned during 1997-1999, a permanent IRIS/GSN station (PMSA), and 3 seismic stations installed at scientific bases, Esperanza (ESPZ), Jubany (JUBA), and King Sejong (KSJ), in South Shetland Islands. All of the seismic stations are located in coast area, and the signal to noise ratios (SNR) are very low. The P-wave model was inverted from 95 earthquakes resulting in 347 ray paths with P- and PKP-wave arrivals. The inverted model shows a strong low velocity anmaly beneath the Bransfield Strait, and a fast anomaly beneath the South Shetland Islands. The low velocity anomaly beneath the Bransfield might be due to a back arc extension, and the fast velocity anomaly beneath the South Shetland Islands could indicates the cold subducted slab.

  14. Antiferromagnetism, f -wave, and chiral p -wave superconductivity in a kagome lattice with possible application to s d2 graphenes

    NASA Astrophysics Data System (ADS)

    Wang, Wan-Sheng; Liu, Yuan-Chun; Xiang, Yuan-Yuan; Wang, Qiang-Hua

    2016-07-01

    We investigate the electronic instabilities in a kagome lattice with Rashba spin-orbital coupling by the unbiased singular-mode functional renormalization group. At the parent 1 /3 filling, the normal state is a quantum spin Hall system. Since the bottom of the conduction band is near the van Hove singularity, the electron-doped system is highly susceptible to competing orders upon electron interactions. The topological nature of the parent system enriches the complexity and novelty of such orders. We find 120∘-type intra-unit-cell antiferromagnetic order, f -wave superconductivity, and chiral p -wave superconductivity with increasing electron doping above the van Hove point. In both types of superconducting phases, there is a mixture of comparable spin singlet and triplet components because of the Rashba coupling. The chiral p -wave superconducting state is characterized by a Chern number Z =1 , supporting a branch of Weyl fermion states on each edge. The model bares close relevance to the so-called s d2 graphenes proposed recently.

  15. P wave attenuation structure below the Tokyo Metropolitan area

    NASA Astrophysics Data System (ADS)

    Panayotopoulos, Y.; Sakai, S.; Nakagawa, S.; Kasahara, K.; Hirata, N.; Aketagawa, T.; Kimura, H.; Lee, C.

    2010-12-01

    The material properties of the complex subduction zone beneath the Tokyo Metropolitan can be estimated by the seismic attenuation Q-1 of seismic waves observed at local seismic stations. The attenuation of seismic waves is represented by the t* attenuation operator that can be estimated by fitting the observed P wave amplitude spectrum to a theoretical spectrum using an ω2 source model. The waveform data used in this study are recorded at the dense seismic array of the Metropolitan Seismic Observation network (MeSO-net). The station network is distributed on five lines with an average spacing of 3 km and in an area with a spacing of 5 km in the central part of Kanto plane. The MeSO-net stations are equipped with a three-component accelerometer at a bottom of a 20-m-deep borehole, signals from which are digitized at a sampling rate of 200 Hz with a dynamic range of 135 dB.The waveforms of 141 earthquakes observed at 226 stations were selected from the Japan Meteorological Agency (JMA) unified earthquake list from January 1st 2010 to August 4th 2010. Only high-quality amplitude spectra of earthquakes with M > 3 were used for the estimation of reliable attenuation parameters. The acceleration waveforms were integrated twice to yield the corresponding displacement vectors, applying a high pass filter to remove the effect of the low-frequency background noise. Taking into account that the majority of the events occurred at depth greater than 30 km a search window of 5 sec starting 1 sec before the P wave arrival was implemented for the creation of the dataset. The t* values were estimated from the amplitude spectra of approximately 33800 P wave waveforms conducting a fast Fourier transform analysis. The Q values for the Tokyo Metropolitan area estimate by this study range from 100 to 500 in the upper 30 km of the crust. A site effect on the attenuation near stations inside a densely populated area is also a possible reason for the large Q variations observed.

  16. Source Time Function of P-wave Acceleration

    NASA Astrophysics Data System (ADS)

    Chen, K. J.

    2015-12-01

    In this study, the site effect of time function of the Taiwan area will be invested. The recorded response function of a single earthquake will be calculated by Complex Demodulation. The path effect of each event-station pair will be estimated by using the forward method with a 3-D attenuation structure. After removing the path effect, the source frequency function of each single event will be obtained by averaging the whole station gotten. Using this source time function to calculate the path effect of the all stations, the theoretic received time frequency function can be obtained. The difference between this theoretic function and the recorded function is the site effect function of the single station. The characterics of the site effect in Taiwan area will be analyzed. Recalculate the path effect and remove the site effect of each station to get the new source time function of P-wave acceleration.

  17. Measurement of inclusive isolated prompt photon production at center of mass energy = 7 TeV with the ATLAS

    NASA Astrophysics Data System (ADS)

    Hance, Michael

    Prompt photons at hadron colliders are useful probes of perturbative quantum chromodynamics (pQCD), and are also found in signatures of new physics. A precise measurement of prompt photon production is both a useful test of theoretical models as well as an important step towards understanding final states that contain energetic photons. This thesis presents a measurement of the inclusive isolated prompt photon production cross section in proton-proton collisions at a center-of-mass energy of s = 7 TeV. The data are collected with the ATLAS detector at the Large Hadron Collider, and correspond to 35 pb-1 of integrated luminosity. The measurement is made in four photon pseudorapidity (etagamma) regions: 0 ≤ |etagamma| < 0.6; 0.6 ≤ |etagamma| < 1.37; 1.52 ≤ |eta gamma| < 1.81; and 1.81 ≤ |etagamma| < 2.37; and covers photon transverse energies ( EgT ) in the range 15 GeV ≤ EgT < 400 GeV. Photon candidates are reconstructed and identified through the use of the ATLAS calorimeter and tracking systems. The residual background, primarily from neutral meson decays, is estimated using in-situ techniques based on observed distributions of the total transverse energy in a narrow cone around the photon candidate. The measurements are compared to predictions from next-to-leading order pQCD calculations, with good agreement for photon transverse energies greater than 25 GeV.

  18. Region of stability derived by center of mass acceleration better identifies individuals with difficulty in sit-to-stand movement.

    PubMed

    Fujimoto, Masahiro; Chou, Li-Shan

    2014-04-01

    Poor performance of sit-to-stand (STS) has been identified as one of the predictors of fall risk among elderly adults. This study examined differences in the whole body center of mass (COM) kinematic variables in relation to the regions of stability between elderly adults with difficulty in STS and healthy individuals. Whole body motion data while performing STS were collected from 10 young, 10 elderly and 10 elderly subjects with difficulty in STS. Young subjects were also asked to stand up with their trunk purposely bent forward. The regions of stability were defined with COM position at seat-off and its instantaneous velocity (ROSv) or peak acceleration (ROSa), using a single-link-plus-foot inverted pendulum model. Peak COM accelerations prior to seat-off differed significantly among groups; however, no significant differences were detected in its velocities at seat-off. The ROSa demonstrated a better ability to discriminate elderly adults with difficulty from healthy individuals. Although a similar COM momentum was observed at seat-off, how the momentum was controlled differed between healthy individuals and individuals with difficulty in STS. ROSa could provide insight into how the COM momentum is controlled prior to seat-off, which could be used to differentiate individuals with functional limitations from healthy individuals. PMID:24259008

  19. Center of Mass Acceleration Feedback Control of Standing Balance by Functional Neuromuscular Stimulation against External Postural Perturbations

    PubMed Central

    Nataraj, Raviraj; Audu, Musa L.; Triolo, Ronald J.

    2013-01-01

    This study investigated the use of center of mass (COM) acceleration feedback for improving performance of a functional neuromuscular stimulation (FNS) control system to restore standing function to a subject with complete, thoracic-level spinal cord injury (SCI). The approach for linearly relating changes in muscle stimulation to changes in COM acceleration was verified experimentally and subsequently produced data to create an input-output map driven by sensor feedback. The feedback gains were systematically tuned to reduce upper extremity (UE) loads applied to an instrumented support device while resisting external postural disturbances. Total body COM acceleration was accurately estimated (> 89% variance explained) using three-dimensional (3-D) outputs of two accelerometers mounted on the pelvis and torso. Compared to constant muscle stimulation employed clinically, feedback control of stimulation reduced UE loading by 33%. COM acceleration feedback is advantageous in constructing a standing neuroprosthesis since it provides the basis for a comprehensive control synergy about a global, dynamic variable and requires minimal instrumentation. Future work should include tuning and testing the feedback control system during functional reaching activity that is more indicative of activities of daily living. PMID:22987499

  20. Modeling the Impact of Space Suit Components and Anthropometry on the Center of Mass of a Seated Crewmember

    NASA Technical Reports Server (NTRS)

    Rajulu, Sudhakar; Blackledge, Christopher; Ferrer, Mike; Margerum, Sarah

    2009-01-01

    The designers of the Orion Crew Exploration Vehicle (CEV) utilize an intensive simulation program in order to predict the launch and landing characteristics of the Crew Impact Attenuation System (CIAS). The CIAS is the energy absorbing strut concept that dampens loads to levels sustainable by the crew during landing and consists of the crew module seat pallet that accommodates four to six seated astronauts. An important parameter required for proper dynamic modeling of the CIAS is knowledge of the suited center of mass (COM) variations within the crew population. Significant center of mass variations across suited crew configurations would amplify the inertial effects of the pallet and potentially create unacceptable crew loading during launch and landing. Established suited, whole-body, and posture-based mass properties were not available due to the uncertainty of the final CEV seat posture and suit hardware configurations. While unsuited segmental center of mass values can be obtained via regression equations from previous studies, building them into a model that was posture dependent with custom anthropometry and integrated suit components proved cumbersome and time consuming. Therefore, the objective of this study was to quantify the effects of posture, suit components, and the expected range of anthropometry on the center of mass of a seated individual. Several elements are required for the COM calculation of a suited human in a seated position: anthropometry; body segment mass; suit component mass; suit component location relative to the body; and joint angles defining the seated posture. Anthropometry and body segment masses used in this study were taken from a selection of three-dimensional human body models, called boundary manikins, which were developed in a previous project. These boundary manikins represent the critical anthropometric dimension extremes for the anticipated astronaut population. Six male manikins and 6 female manikins, representing a

  1. Center of Mass Acceleration Feedback Control of Functional Neuromuscular Stimulation for Standing in the Presence of Internal Postural Perturbations

    PubMed Central

    Audu, Musa L.; Triolo, Ronald J.

    2013-01-01

    This study determined the feasibility and performance of center of mass (COM) acceleration feedback control of a neuroprosthesis utilizing functional neuromuscular stimulation (FNS) to restore standing balance to a single subject paralyzed by a motor and sensory complete, thoracic-level spinal cord injury (SCI). An artificial neural network (ANN) was created to map gain-modulated changes in total body COM acceleration estimated from body-mounted sensors to optimal changes in stimulation required to maintain standing. Feedback gains were systematically tuned to minimize the upper extremity (UE) loads applied by the subject to an instrumented support device during internally generated postural perturbations produced by volitional reaching and object manipulation. Total body COM acceleration was accurately estimated (> 90% variance explained) from two three-dimensional (3-D) accelerometers mounted on the pelvis and torso. Compared to constant muscle stimulation employed clinically, COM acceleration feedback control of stimulation improved standing performance by reducing the UE loading required to resist internal postural disturbances by 27%. This case study suggests that COM acceleration feedback could potentially be advantageous in a standing neuroprosthesis since it can be implemented with only a few feedback parameters and requires minimal instrumentation for comprehensive, 3-D control of dynamic standing function. PMID:23299260

  2. Non-actively controlled double-inverted-pendulum-like dynamics can minimize center of mass acceleration during human quiet standing.

    PubMed

    Suzuki, Yasuyuki; Morimoto, Hiroki; Kiyono, Ken; Morasso, Pietro; Nomura, Taishin

    2015-08-01

    Multiple joint movements during human quiet standing exhibit characteristic inter-joint coordination, shortly referred to as reciprocal relationship, in which angular acceleration of the hip joint is linearly and negatively correlated with that of the ankle joint (antiphase coordination) and, moreover, acceleration of the center of mass (CoM) of the double-inverted-pendulum (DIP) model of the human body is close to zero constantly. A question considered in this study is whether the reciprocal relationship is established by active neural control of the posture, or rather it is a biomechanical consequence of non-actively controlled body dynamics. To answer this question, we consider a DIP model of quiet standing, and show that the reciprocal relationship always holds by Newton's second law applied to the DIP model with human anthropometric dimensions, regardless of passive and active joint torque patterns acting on the ankle and hip joints. We then show that characteristic frequencies included in experimental sway trajectories with the reciprocal relationship match with harmonics of the eigenfrequency of the stable antiphase eigenmode of the non-actively controlled DIP-like unstable body dynamics. The results suggest that non-actively controlled DIP-like mechanical dynamics is a major cause of the minimization of the CoM acceleration during quiet standing, which is consistent with a type of control strategy that allows switching off active neural control intermittently for suitable periods of time during quiet standing. PMID:26736538

  3. Relationship between macro-fracture density, P-wave velocity, and permeability of coal

    NASA Astrophysics Data System (ADS)

    Wang, Haichao; Pan, Jienan; Wang, Sen; Zhu, Haitao

    2015-06-01

    This study was undertaken to determine the quantitative relationship between macro-fracture density, P-wave velocity, porosity and permeability of different coal rank samples from mining areas in North China. The coal sample permeability shows an exponential growth with increasing fracture density. The relation between P-wave velocity and porosity is power function and P-wave velocity decreases with the increasing porosity. P-wave velocity linearly or nonlinearly decreases with the increase of fracture density in the selected coal samples (0.73-3.59% Ro). However, the overall trend is that P-wave velocity decreases with an increase in macro-fracture density. The permeability of coal samples linearly decreases with the increase of P-wave velocity. The quantitative relationship between P-wave velocity and permeability could provide reference for the further study of permeability predicting.

  4. Estimation of Radiated Seismic Energy from Teleseismic P Waves

    NASA Astrophysics Data System (ADS)

    Kiuchi, R.; Mori, J. J.

    2013-12-01

    Earthquake radiated energy is a fundamental parameter for understanding source physics. Using teleseismic waveforms, we can estimate the radiated energy for a wide range of focal mechanisms and tectonic setting. We are especially interested in studying the apparent stress (rigidity multiplied by the ratio of radiated energy to seismic moment) of strike-slip earthquakes in the oceanic lithosphere, for which there are often high reported values (Choy and McGarr, 2002). Estimates of radiated energy from teleseismic P waves can be unstable, because take-off angles from the source are often close to nodes in the focal mechanisms, which can cause large variations in the estimated values of the apparent stress. In this study, we use only P waves for the teleseismic waveform, because of the strong attenuation of teleseismic S waves and interference with other phases. We use data recorded by teleseismic stations (epicentral distances of 30 to 90deg) recorded on the GSN network and focal mechanisms published by USGS and Global CMT Project. For the teleseismic waveforms, we need to account for the radiation pattern of the direct P and depth phase, pP and sP (Boatwright and Choy, 1986). For strike-slip events with where many data are close to nodes in the focal mechanisms, this is a large and often unstable correction. We use an improved method which takes into account a range of values for the strike, dip and rake angles. Also, we use station corrections determined from a selected set of well determined events. We show the result of estimated radiated seismic energy for 188 recent earthquakes (>Mw 7.0, since 2000 ). We discuss the differences of the radiated energy as a function of focal mechanisms, and oceanic/continental sources. Fig. Radiated seismic energy and correction for radiation pattern calculated using a range of focal mechanisms.

  5. Entanglement in fermionic systems

    SciTech Connect

    Banuls, Mari-Carmen; Cirac, J. Ignacio; Wolf, Michael M.

    2007-08-15

    The anticommuting properties of fermionic operators, together with the presence of parity conservation, affect the concept of entanglement in a composite fermionic system. Hence different points of view can give rise to different reasonable definitions of separable and entangled states. Here we analyze these possibilities and the relationship between the different classes of separable states. The behavior of the various classes when taking multiple copies of a state is also studied, showing that some of the differences vanish in the asymptotic regime. In particular, in the case of only two fermionic modes all the classes become equivalent in this limit. We illustrate the differences and relations by providing a complete characterization of all the sets defined for systems of two fermionic modes. The results are applied to Gibbs states of infinite chains of fermions whose interaction corresponds to a XY Hamiltonian with transverse magnetic field.

  6. Bold Diagrammatic Monte Carlo for Fermionic and Fermionized Systems

    NASA Astrophysics Data System (ADS)

    Svistunov, Boris

    2013-03-01

    In three different fermionic cases--repulsive Hubbard model, resonant fermions, and fermionized spins-1/2 (on triangular lattice)--we observe the phenomenon of sign blessing: Feynman diagrammatic series features finite convergence radius despite factorial growth of the number of diagrams with diagram order. Bold diagrammatic Monte Carlo technique allows us to sample millions of skeleton Feynman diagrams. With the universal fermionization trick we can fermionize essentially any (bosonic, spin, mixed, etc.) lattice system. The combination of fermionization and Bold diagrammatic Monte Carlo yields a universal first-principle approach to strongly correlated lattice systems, provided the sign blessing is a generic fermionic phenomenon. Supported by NSF and DARPA

  7. Systematic variation of prosthetic foot spring affects center-of-mass mechanics and metabolic cost during walking

    PubMed Central

    Zelik, Karl E.; Collins, Steven H.; Adamczyk, Peter G.; Segal, Ava D.; Klute, Glenn K.; Morgenroth, David C.; Hahn, Michael E.; Orendurff, Michael S.; Czerniecki, Joseph M.; Kuo, Arthur D.

    2014-01-01

    Lower-limb amputees expend more energy to walk than non-amputees and have an elevated risk of secondary disabilities. Insufficient push-off by the prosthetic foot may be a contributing factor. We aimed to systematically study the effect of prosthetic foot mechanics on gait, to gain insight into fundamental prosthetic design principles. We varied a single parameter in isolation, the energy-storing spring in a prototype prosthetic foot, the Controlled Energy Storage and Return (CESR) foot, and observed the effect on gait. Subjects walked on the CESR foot with three different springs. We performed parallel studies on amputees and on non-amputees wearing prosthetic simulators. In both groups, spring characteristics similarly affected ankle and body center-of-mass (COM) mechanics and metabolic cost. Softer springs led to greater energy storage, energy return and prosthetic limb COM push-off work. But metabolic energy expenditure was lowest with a spring of intermediate stiffness, suggesting biomechanical disadvantages to the softest spring despite its greater push-off. Disadvantages of the softest spring may include excessive heel displacements and COM collision losses. We also observed some differences in joint kinetics between amputees and non-amputees walking on the prototype foot. During prosthetic push-off, amputees exhibited reduced energy transfer from the prosthesis to the COM along with increased hip work, perhaps due to greater energy dissipation at the knee. Nevertheless, the results indicate that spring compliance can contribute to push-off, but with biomechanical trade-offs that limit the degree to which greater push-off might improve walking economy. PMID:21708509

  8. Wireless Tri-Axial Trunk Accelerometry Detects Deviations in Dynamic Center of Mass Motion Due to Running-Induced Fatigue

    PubMed Central

    2015-01-01

    Small wireless trunk accelerometers have become a popular approach to unobtrusively quantify human locomotion and provide insights into both gait rehabilitation and sports performance. However, limited evidence exists as to which trunk accelerometry measures are suitable for the purpose of detecting movement compensations while running, and specifically in response to fatigue. The aim of this study was therefore to detect deviations in the dynamic center of mass (CoM) motion due to running-induced fatigue using tri-axial trunk accelerometry. Twenty runners aged 18–25 years completed an indoor treadmill running protocol to volitional exhaustion at speeds equivalent to their 3.2 km time trial performance. The following dependent measures were extracted from tri-axial trunk accelerations of 20 running steps before and after the treadmill fatigue protocol: the tri-axial ratio of acceleration root mean square (RMS) to the resultant vector RMS, step and stride regularity (autocorrelation procedure), and sample entropy. Running-induced fatigue increased mediolateral and anteroposterior ratios of acceleration RMS (p < .05), decreased the anteroposterior step regularity (p < .05), and increased the anteroposterior sample entropy (p < .05) of trunk accelerometry patterns. Our findings indicate that treadmill running-induced fatigue might reveal itself in a greater contribution of variability in horizontal plane trunk accelerations, with anteroposterior trunk accelerations that are less regular from step-to-step and are less predictable. It appears that trunk accelerometry parameters can be used to detect deviations in dynamic CoM motion induced by treadmill running fatigue, yet it is unknown how robust or generalizable these parameters are to outdoor running environments. PMID:26517261

  9. Variation in center of mass estimates for extant sauropsids and its importance for reconstructing inertial properties of extinct archosaurs.

    PubMed

    Allen, Vivian; Paxton, Heather; Hutchinson, John R

    2009-09-01

    Inertial properties of animal bodies and segments are critical input parameters for biomechanical analysis of standing and moving, and thus are important for paleobiological inquiries into the broader behaviors, ecology and evolution of extinct taxa such as dinosaurs. But how accurately can these be estimated? Computational modeling was used to estimate the inertial properties including mass, density, and center of mass (COM) for extant crocodiles (adult and juvenile Crocodylus johnstoni) and birds (Gallus gallus; junglefowl and broiler chickens), to identify the chief sources of variation and methodological errors, and their significance. High-resolution computed tomography scans were segmented into 3D objects and imported into inertial property estimation software that allowed for the examination of variable body segment densities (e.g., air spaces such as lungs, and deformable body outlines). Considerable biological variation of inertial properties was found within groups due to ontogenetic changes as well as evolutionary changes between chicken groups. COM positions shift in variable directions during ontogeny in different groups. Our method was repeatable and the resolution was sufficient for accurate estimations of mass and density in particular. However, we also found considerable potential methodological errors for COM related to (1) assumed body segment orientation, (2) what frames of reference are used to normalize COM for size-independent comparisons among animals, and (3) assumptions about tail shape. Methods and assumptions are suggested to minimize these errors in the future and thereby improve estimation of inertial properties for extant and extinct animals. In the best cases, 10%-15% errors in these estimates are unavoidable, but particularly for extinct taxa errors closer to 50% should be expected, and therefore, cautiously investigated. Nonetheless in the best cases these methods allow rigorous estimation of inertial properties. PMID:19711477

  10. The gaits of primates: center of mass mechanics in walking, cantering and galloping ring-tailed lemurs, Lemur catta.

    PubMed

    O'Neill, Matthew C; Schmitt, Daniel

    2012-05-15

    Most primates, including lemurs, have a broad range of locomotor capabilities, yet much of the time, they walk at slow speeds and amble, canter or gallop at intermediate and fast speeds. Although numerous studies have investigated limb function during primate quadrupedalism, how the center of mass (COM) moves is not well understood. Here, we examined COM energy, work and power during walking, cantering and galloping in ring-tailed lemurs, Lemur catta (N=5), over a broad speed range (0.43-2.91 m s(-1)). COM energy recoveries were substantial during walking (35-71%) but lower during canters and gallops (10-51%). COM work, power and collisional losses increased with speed. The positive COM works were 0.625 J kg(-1) m(-1) for walks and 1.661 J kg(-1) m(-1) for canters and gallops, which are in the middle range of published values for terrestrial animals. Although some discontinuities in COM mechanics were evident between walking and cantering, there was no apparent analog to the trot-gallop transition across the intermediate and fast speed range (dimensionless v>0.75, Fr>0.5). A phenomenological model of a lemur cantering and trotting at the same speed shows that canters ensure continuous contact of the body with the substrate while reducing peak vertical COM forces, COM stiffness and COM collisions. We suggest that cantering, rather than trotting, at intermediate speeds may be tied to the arboreal origins of the Order Primates. These data allow us to better understand the mechanics of primate gaits and shed new light on primate locomotor evolution. PMID:22539740

  11. Whole Body Center of Mass Estimation with Portable Sensors: Using the Statically Equivalent Serial Chain and a Kinect

    PubMed Central

    González, Alejandro; Hayashibe, Mitsuhiro; Bonnet, Vincent; Fraisse, Philippe

    2014-01-01

    The trajectory of the whole body center of mass (CoM) is useful as a reliable metric of postural stability. If the evaluation of a subject-specific CoM were available outside of the laboratory environment, it would improve the assessment of the effects of physical rehabilitation. This paper develops a method that enables tracking CoM position using low-cost sensors that can be moved around by a therapist or easily installed inside a patient's home. Here, we compare the accuracy of a personalized CoM estimation using the statically equivalent serial chain (SESC) method and measurements obtained with the Kinect to the case of a SESC obtained with high-end equipment (Vicon). We also compare these estimates to literature-based ones for both sensors. The method was validated with seven able-bodied volunteers for whom the SESC was identified using 40 static postures. The literature-based estimation with Vicon measurements had a average error 24.9 ± 3.7 mm; this error was reduced to 12.8 ± 9.1 mm with the SESC identification. When using Kinect measurements, the literature-based estimate had an error of 118.4 ± 50.0 mm, while the SESC error was 26.6 ± 6.0 mm. The subject-specific SESC estimate using low-cost sensors has an equivalent performance as the literature-based one with high-end sensors. The SESC method can improve CoM estimation of elderly and neurologically impaired subjects by considering variations in their mass distribution. PMID:25215943

  12. Redirection of center-of-mass velocity during the step-to-step transition of human walking.

    PubMed

    Adamczyk, Peter G; Kuo, Arthur D

    2009-08-01

    Simple dynamic walking models based on the inverted pendulum predict that the human body's center of mass (COM) moves along an arc during each step, with substantial work performed to redirect the COM velocity in the step-to-step transition between arcs. But humans do not keep the stance leg perfectly straight and need not redirect their COM velocity precisely as predicted. We therefore tested a pendulum-based model against a wide range of human walking data. We examined COM velocity and work data from normal human subjects (N=10) walking at 24 combinations of speed (0.75 to 2.0 m s(-1)) and step length. These were compared against model predictions for the angular redirection of COM velocity and the work performed on the COM during redirection. We found that the COM is redirected through angular changes increasing approximately linearly with step length (R(2)=0.68), with COM work increasing with the squared product of walking speed and step length (R(2)=0.82), roughly in accordance with a simple dynamic walking model. This model cannot, however, predict the duration of COM redirection, which we quantified with two empirical measures, one based on angular COM redirection and the other on work. Both indicate that the step-to-step transition begins before and ends after double support and lasts about twice as long - approximately 20-27% of a stride. Although a rigid leg model can predict trends in COM velocity and work, the non-rigid human leg performs the step-to-step transition over a duration considerably exceeding that of double support. PMID:19648412

  13. Muscle mechanical work requirements during normal walking: the energetic cost of raising the body's center-of-mass is significant.

    PubMed

    Neptune, R R; Zajac, F E; Kautz, S A

    2004-06-01

    Inverted pendulum models of walking predict that little muscle work is required for the exchange of body potential and kinetic energy in single-limb support. External power during walking (product of the measured ground reaction force and body center-of-mass (COM) velocity) is often analyzed to deduce net work output or mechanical energetic cost by muscles. Based on external power analyses and inverted pendulum theory, it has been suggested that a primary mechanical energetic cost may be associated with the mechanical work required to redirect the COM motion at the step-to-step transition. However, these models do not capture the multi-muscle, multi-segmental properties of walking, co-excitation of muscles to coordinate segmental energetic flow, and simultaneous production of positive and negative muscle work. In this study, a muscle-actuated forward dynamic simulation of walking was used to assess whether: (1). potential and kinetic energy of the body are exchanged with little muscle work; (2). external mechanical power can estimate the mechanical energetic cost for muscles; and (3.) the net work output and the mechanical energetic cost for muscles occurs mostly in double support. We found that the net work output by muscles cannot be estimated from external power and was the highest when the COM moved upward in early single-limb support even though kinetic and potential energy were exchanged, and muscle mechanical (and most likely metabolic) energetic cost is dominated not only by the need to redirect the COM in double support but also by the need to raise the COM in single support. PMID:15111069

  14. Topological D +p -wave superconductivity in Rashba systems

    NASA Astrophysics Data System (ADS)

    Yoshida, Tomohiro; Yanase, Youichi

    2016-02-01

    We show two-dimensional "strong" topological superconductivity in d -wave superconductors (SCs). Although the topological invariant of the bulk wave function cannot be defined in dx2-y2-wave and dx y-wave SCs because of nodal excitations, the bulk energy spectrum of d -wave SCs on a substrate is fully gapped in a magnetic field. Then the superconducting state is specified by a nontrivial Chern number, and hence topologically nontrivial properties are robust against disorders and interactions. We discuss high-temperature topological superconductivity in cuprate SCs recently fabricated on a substrate. Furthermore, we show that the three-dimensional noncentrosymmetric d -wave SC is a Weyl SC hosting topologically protected Weyl nodes. Noncentrosymmetric heavy-fermion SCs, such as CeRhSi3 and CeIrSi3, are candidates for Weyl SCs.

  15. Bootstrapping 3D fermions

    NASA Astrophysics Data System (ADS)

    Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran

    2016-03-01

    We study the conformal bootstrap for a 4-point function of fermions < ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge C T . We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N . We also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.

  16. Mantle-Lid P Wave Attenuation in the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Lee, K.; Hong, T.

    2012-12-01

    The mantle-lid P wave, Pn, is the first arrival phase in regional distances. The Pn waves are widely analyzed for estimation of event sizes. Also, it is known that analysis of Pn waves is effective for discrimination of nuclear explosions from natural earthquakes. The attenuation of Pn waves provides us information on medium properties in mantle lid. It is crucial to understand the nature of Pn attenuation for correct estimation of event sizes from Pn amplitudes. We investigate the lateral variation of Pn attenuation in the mantle lid of the Korean Peninsula from vertical regional seismograms for events around the Korean Peninsula and Japanese islands. The number of events is 149, and the focal depths are less than 50 km. The seismic records with signal-to-noise ratios greater than 1.5 are analyzed. The number of stations is 121. The Pn quality factors are calculated using a two-station method in which ratios of Pn displacement spectra of stations on the same azimuths are used. The power-law frequency dependence term is estimated using a least-squares fitting for quality factors at frequencies from 0.37 Hz to 25 Hz. The number of station pairs is 3317. The average quality factor at 1 Hz is determined to be about 67, which is consistent with previous studies. We present the resultant Pn attenuation model, and discuss the correlations with geological and geophysical properties in the medium.

  17. Hammering Yucca Flat, Part One: P-Wave Velocity

    NASA Astrophysics Data System (ADS)

    Tang, D. G.; Abbott, R. E.; Preston, L. A.; Hampshire, J. B., II

    2015-12-01

    Explosion-source phenomenology is best studied when competing signals (such as instrument, site, and propagation effects), are well understood. The second phase of the Source Physics Experiments (SPE), is moving from granite geology to alluvium geology at Yucca Flat, Nevada National Security Site. To improve subsurface characterization of Yucca Flat (and therefore better understand propagation and site effects), an active-source seismic survey was conducted using a novel 13,000-kg impulsive hammer source. The source points, spaced 200 m apart, covered a N-S transect spanning 18 km. Three component, 2-Hz geophones were used to record useable signals out to 10 km. We inverted for P-wave velocity by computing travel times using a finite-difference 3D eikonal solver, and then compared that to the picked travel times using a linearized iterative inversion scheme. Preliminary results from traditional reflection processing methods are also presented. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  18. P Wave Velocity Structure Beneath the Baikal Rift Axis

    NASA Astrophysics Data System (ADS)

    Brazier, R. A.; Nyblade, A. A.; Boman, E. C.

    2001-12-01

    Over 100 p wave travel times from the 1500 km en echelon Baikal Rift system are used in this study.The events range 3 to 13 degrees from Talaya, Russia (TLY) along the axis of southwest northeast trending rift in East Siberia. A Herglotz Wiechert inversion of these events resolved a crust of 6.4 km/s and a gradient in the mantle starting at 35 km depth and 7.7 km/s down to 200 km depth and 8.2 km/s. This is compatible with Gao et al,1994 cross sectional structure which cuts the rift at about 400km from TLY. The Baikal Rift hosts the deepest lake and is the most seismically active rift in the world. It is one of the few continental rifts, it separates the Siberian craton and the Syan-Baikal mobile fold belt. Two events, the March 21 1999 magnitude 5.7 earthquake 638 km from TLY and the November 13th 1995 magnitude 5.9 earthquake 863 km from TLY were modeled for there PnL wave structure using the discrete wavenumber method and the Harvard CMT solutions with adjusted depths from p-pP times. The PnL signals match well. A genetic algorithm will used to perturb the velocity structure and compare to a selection of the events between 3 and 13 degrees many will require moment tensor solutions.

  19. Direct imaging of the coda of teleseismic P waves

    NASA Astrophysics Data System (ADS)

    Pavlis, Gary L.

    This paper reviews the theoretical background of existing techniques for direct imaging of the coda of teleseismic P waves. A unifying theme of all approaches is the Born series for elastic wave scattering. Inversion methods for one-dimensional structure commonly included multiply scattered waves while all existing two and three-dimensional implementations are limited by a single scattering approximation that defines a linear inverse problem in material property perturbations. The problem has an analytic inverse because the forward problem can be cast as a generalized Radon transform with line/surface integrals along single scatterer isochrons. The inverse Radon transform can then be applied to estimate scattering strength at a given point as a linear combination of all data that match a time and polarization constraint. I describe how backprojection, Kirchhoff approximations, and inverse scattering approaches are related to the fundamental scattering equations. I introduce a new concept called the exploding converter model that is a useful physical model for understanding imaging techniques and show how it is related to the Born integral equation. Finally, I discuss limitation on imaging imposed by deconvolution of the incident wavefield. I show that deconvolution is based on an incorrect assumption because it neglects a propagator term from the base of the imaging volume to the free surface. I give the correct form of the deconvolution operator and suggest it may be possible to improve deconvolution through application of downward continuation operators that enter in these equations.

  20. Direct Imaging of the Coda of Teleseismic P waves

    NASA Astrophysics Data System (ADS)

    Pavlis, G. L.

    2002-12-01

    This paper reviews the theoretical background of existing techniques for direct imaging of the coda of teleseismic P waves. A unifying theme of all approaches is the Born series for elastic wave scattering. Inversion methods for one-dimensional structure commonly included multiply scattered waves while all existing two and three-dimensional implementations are limited by a single scattering approximation that defines a linear inverse problem in material property perturbations. The problem has an analytic inverse because the forward problem can be cast as a generalized Radon transform with line/surface integrals along single scatterer isocrons. The inverse Radon transform can then be applied to estimate scattering strength at a given point as a linear combination of all data that match a time and polarization constraint. I describe how backprojection, Kirchoff approximations, and inverse scattering approachs are related to the fundamental scattering equations. I introduce a new concept called the exploding converter model that is a useful physical model for understanding imaging techniques and show how it is related to the Born integral equation. Finally, I discuss limitation on imaging imposed by deconvolution of the incident wavefield. I show that deconvolution is based on an incorrect assumption because it neglects a propagator term from the base of the imaging volume to the free surface. I give the correct form of the deconvolution operator and suggest it may be possible to improve deconvolution through application of downward continuation operators that enter in these equations.

  1. Tunable ground states in helical p-wave Josephson junctions

    NASA Astrophysics Data System (ADS)

    Cheng, Qiang; Zhang, Kunhua; Yu, Dongyang; Chen, Chongju; Zhang, Yinhan; Jin, Biao

    2016-07-01

    We study new types of Josephson junctions composed of helical p-wave superconductors with {k}x\\hat{x}+/- {k}y\\hat{y} and {k}y\\hat{x}+/- {k}x\\hat{y}-pairing symmetries using quasi-classical Green’s functions with generalized Riccati parametrization. The junctions can host rich ground states: π phase, 0 + π phase, φ 0 phase and φ phase. The phase transition can be tuned by rotating the magnetization in the ferromagnetic interface. We present the phase diagrams in the parameter space formed by the orientation of the magnetization or by the magnitude of the interfacial potentials. The selection rules for the lowest order current which are responsible for the formation of the rich phases are summarized from the current-phase relations based on the numerical calculation. We construct a Ginzburg–Landau type of free energy for the junctions with d-vectors and the magnetization, which not only reveals the interaction forms of spin-triplet superconductivity and ferromagnetism, but can also directly lead to the selection rules. In addition, the energies of the Andreev bound states and the novel symmetries in the current-phase relations are also investigated. Our results are helpful both in the prediction of novel Josephson phases and in the design of quantum circuits.

  2. Accurate tremor locations from coherent S and P waves

    NASA Astrophysics Data System (ADS)

    Armbruster, John G.; Kim, Won-Young; Rubin, Allan M.

    2014-06-01

    Nonvolcanic tremor is an important component of the slow slip processes which load faults from below, but accurately locating tremor has proven difficult because tremor rarely contains clear P or S wave arrivals. Here we report the observation of coherence in the shear and compressional waves of tremor at widely separated stations which allows us to detect and accurately locate tremor events. An event detector using data from two stations sees the onset of tremor activity in the Cascadia tremor episodes of February 2003, July 2004, and September 2005 and confirms the previously reported south to north migration of the tremor. Event detectors using data from three and four stations give Sand P arrival times of high accuracy. The hypocenters of the tremor events fall at depths of ˜30 to ˜40 km and define a narrow plane dipping at a shallow angle to the northeast, consistent with the subducting plate interface. The S wave polarizations and P wave first motions define a source mechanism in agreement with the northeast convergence seen in geodetic observations of slow slip. Tens of thousands of locations determined by constraining the events to the plate interface show tremor sources highly clustered in space with a strongly similar pattern of sources in the three episodes examined. The deeper sources generate tremor in minor episodes as well. The extent to which the narrow bands of tremor sources overlap between the three major episodes suggests relative epicentral location errors as small as 1-2 km.

  3. The Mysteries of Fermions

    NASA Astrophysics Data System (ADS)

    Weiner, Richard M.

    2010-05-01

    It is conjectured that all known fermions are topological solitons. This could explain the non-observation of bosonic leptons and baryons and provide a physical mechanism for the Pauli exclusion principle.

  4. Fermions from classical statistics

    SciTech Connect

    Wetterich, C.

    2010-12-15

    We describe fermions in terms of a classical statistical ensemble. The states {tau} of this ensemble are characterized by a sequence of values one or zero or a corresponding set of two-level observables. Every classical probability distribution can be associated to a quantum state for fermions. If the time evolution of the classical probabilities p{sub {tau}} amounts to a rotation of the wave function q{sub {tau}}(t)={+-}{radical}(p{sub {tau}}(t)), we infer the unitary time evolution of a quantum system of fermions according to a Schroedinger equation. We establish how such classical statistical ensembles can be mapped to Grassmann functional integrals. Quantum field theories for fermions arise for a suitable time evolution of classical probabilities for generalized Ising models.

  5. Canonical gravity with fermions

    SciTech Connect

    Bojowald, Martin; Das, Rupam

    2008-09-15

    Canonical gravity in real Ashtekar-Barbero variables is generalized to allow for fermionic matter. The resulting torsion changes several expressions in Holst's original vacuum analysis, which are summarized here. This in turn requires adaptations to the known loop quantization of gravity coupled to fermions, which is discussed on the basis of the classical analysis. As a result, parity invariance is not manifestly realized in loop quantum gravity.

  6. Determination of Geometrical Loci of the Earth's Center of Mass and its Cycles Based on the "Pulsating Mantle Hypothesis"

    NASA Astrophysics Data System (ADS)

    Gholibeigian, H.; AmirShahkarami, A.

    2013-05-01

    If we suppose that the inner core's center is overlap on the Earth's center, in case of no external gravity attractions, then we can say that the Earth's center of mass (geo-center) will be approximately overlapped on the Earth's center. But actually this is not the story. From view of the Pulsating Mantle Hypothesis which presented by us in AGU Fall Meeting 2012, PA23A-1960, in brief; two phenomena; Inner Core Dislocation and Outer Core Bulge have appeared inside the Earth due to unbalanced gravitational attraction of the Sun and the Moon. These two phenomena in their diurnal rotation around the Earth's center produce a huge mass transfer, momentum of inertia changes, Earth's spin changes, loading from inside out the Earth and forced convection systems in the outer core and the mantle. Tectonic plates movement, volcanic, ...and earthquake are their other results. distance between these two centers varies permanently in magnitude and direction. inner core's center has diurnal, monthly and yearly cycles around the Earth's center. Inner core's diurnal flow generates mass displacement in the Earth's outer core and consequently the location of geo-center isn't stable and varies between the Earth's center and dislocated inner core's center. Geo-center (gravity center) permanently follows the inner core's center towards the external gravitational attraction field and like it has diurnal, monthly and yearly cycles and its distance to the Earth's center varies permanently in magnitude and direction. These variations generate permanent apparent (true) solar day length variation which is tens of seconds in a year, NASA Eclipse Web Site, and for year 2010, its highest magnitude variation (in new Moon/solar eclipse) was 86,471 seconds and its lowest magnitude (in full moon/lunar eclipse) was 86,325 seconds, Universday Web Site. As we can see, 146 seconds variations continuously in true solar day length during a year represents huge and rapid mass transfer inside the Earth. In

  7. Interacting quantum walkers: two-body bosonic and fermionic bound states

    NASA Astrophysics Data System (ADS)

    Krapivsky, P. L.; Luck, J. M.; Mallick, K.

    2015-11-01

    We investigate the dynamics of bound states of two interacting particles, either bosons or fermions, performing a continuous-time quantum walk on a one-dimensional lattice. We consider the situation where the distance between both particles has a hard bound, and the richer situation where the particles are bound by a smooth confining potential. The main emphasis is on the velocity characterizing the ballistic spreading of these bound states, and on the structure of the asymptotic distribution profile of their center-of-mass coordinate. The latter profile generically exhibits many internal fronts.

  8. Accurate source location from P waves scattered by surface topography

    NASA Astrophysics Data System (ADS)

    Wang, N.; Shen, Y.

    2015-12-01

    Accurate source locations of earthquakes and other seismic events are fundamental in seismology. The location accuracy is limited by several factors, including velocity models, which are often poorly known. In contrast, surface topography, the largest velocity contrast in the Earth, is often precisely mapped at the seismic wavelength (> 100 m). In this study, we explore the use of P-coda waves generated by scattering at surface topography to obtain high-resolution locations of near-surface seismic events. The Pacific Northwest region is chosen as an example. The grid search method is combined with the 3D strain Green's tensor database type method to improve the search efficiency as well as the quality of hypocenter solution. The strain Green's tensor is calculated by the 3D collocated-grid finite difference method on curvilinear grids. Solutions in the search volume are then obtained based on the least-square misfit between the 'observed' and predicted P and P-coda waves. A 95% confidence interval of the solution is also provided as a posterior error estimation. We find that the scattered waves are mainly due to topography in comparison with random velocity heterogeneity characterized by the von Kάrmάn-type power spectral density function. When only P wave data is used, the 'best' solution is offset from the real source location mostly in the vertical direction. The incorporation of P coda significantly improves solution accuracy and reduces its uncertainty. The solution remains robust with a range of random noises in data, un-modeled random velocity heterogeneities, and uncertainties in moment tensors that we tested.

  9. Center-of-mass effects on the quasihole spectroscopic factors in the {sup 16}O(e,e{sup {prime}}p) reaction

    SciTech Connect

    Van Neck, D.; Waroquier, M.; Dieperink, A.E.; Pieper, S.C.; Pandharipande, V.R.

    1998-05-01

    The spectroscopic factors for the low-lying quasihole states observed in the {sup 16}O(e,e{sup {prime}}p){sup 15}N reaction are reinvestigated with a variational Monte Carlo calculation for the structure of the initial and final nucleus. A computational error in a previous report is rectified. It is shown that a proper treatment of center-of-mass motion does not lead to a reduction of the spectroscopic factor for p-shell quasihole states, but rather to a 7{percent} enhancement. This is in agreement with analytical results obtained in the harmonic oscillator model. The center-of-mass effect worsens the discrepancy between present theoretical models and the experimentally observed single-particle strength. We discuss the present status of this problem, including some other mechanisms that may be relevant in this respect. {copyright} {ital 1998} {ital The American Physical Society}

  10. a Study of Positron Electron Going to Positive Pion Negative Pion Neutral Pion Neutral Pion at 3.090 GEV Center of Mass Energy

    NASA Astrophysics Data System (ADS)

    McGowan, John Francis, III

    The process e^+e^-to pi^+pi^-pi^0pi ^0 is studied at a center of mass energy of 3.090 GeV, the J/psi center of mass energy, by the Mark III detector at SPEAR. The branching ratios for psitopi^+pi ^-pi^0pi^0 and several background processes are measured: psi topi^+pi^-pi^0 pi^0pi^0, psi to K^+/- K^mppi^0 pi^0, and psito K^+/-pi^mppi^0 pi^0. Upper limits on e^+e ^-torho^+rho^- are derived. Evidence is presented that the isobar model of low-energy hadronic interactions may not apply to e ^+e^-topi^+pi^ -pi^0pi^0. Suggestions for further research are made.

  11. The correlations between the saturated and dry P-wave velocity of rocks.

    PubMed

    Kahraman, S

    2007-11-01

    Sometimes engineers need to estimate the wet-rock P-wave velocity from the dry-rock P-wave velocity. An estimation equation embracing all rock classes will be useful for the rock engineers. To investigate the predictability of wet-rock P-wave velocity from the dry-rock P-wave velocity, P-wave velocity measurements were performed on 41 different rock types, 11 of which were igneous, 15 of which were sedimentary and 15 of which was metamorphic. In addition to the dry- and wet-rock P-wave velocity measurements, the P-wave velocity changing as a function of saturation degree was studied. Moreover, dry-rock S-wave velocity measurements were conducted. The test results were modeled using Gassmann's and Wood's theory and it was seen that the measured data did not fit the theories. The unconformity is due to the fact that the theories are valid for high-porosity unconsolidated sediments at low frequencies. Gassmann's equation was modified for the rocks except high-porosity unconsolidated sediments. The dry- and wet-rock P-wave velocity values were evaluated using regression analysis. A strong linear correlation between the dry- and wet-rock P-wave velocities was found. Regression analyses were repeated for the rock classes and it was shown that correlation coefficients were increased. Concluding remark is that the derived equations can be used for the prediction of wet-rock P-wave velocity from the dry-rock P-wave velocity. PMID:17624388

  12. Superballistic center-of-mass motion in one-dimensional attractive Bose gases: Decoherence-induced Gaussian random walks in velocity space

    NASA Astrophysics Data System (ADS)

    Weiss, Christoph; Cornish, Simon L.; Gardiner, Simon A.; Breuer, Heinz-Peter

    2016-01-01

    We show that the spreading of the center-of-mass density of ultracold attractively interacting bosons can become superballistic in the presence of decoherence, via one-, two-, and/or three-body losses. In the limit of weak decoherence, we analytically solve the numerical model introduced in Weiss et al. [Phys. Rev. A 91, 063616 (2015)], 10.1103/PhysRevA.91.063616. The analytical predictions allow us to identify experimentally accessible parameter regimes for which we predict superballistic spreading of the center-of-mass density. Ultracold attractive Bose gases form weakly bound molecules, quantum matter-wave bright solitons. Our computer simulations combine ideas from classical field methods ("truncated Wigner") and piecewise deterministic stochastic processes. While the truncated Wigner approach to use an average over classical paths as a substitute for a quantum superposition is often an uncontrolled approximation, here it predicts the exact root-mean-square width when modeling an expanding Gaussian wave packet. In the superballistic regime, the leading order of the spreading of the center-of-mass density can thus be modeled as a quantum superposition of classical Gaussian random walks in velocity space.

  13. Medically treated anorexia nervosa is associated with normal P wave parameters.

    PubMed

    Nussinovitch, Moshe; Gur, Eitan; Nussinovitch, Naomi; Kaminer, Keren; Volovitz, Benjamin; Nussinovitch, Udi

    2012-07-30

    Anorexia nervosa (AN) is an increasingly common medical condition. Some studies have demonstrated an increased prevalence of atrial premature contractions and anatomical changes in AN patients. Our aim was to investigate P wave parameters and P wave dispersion, an electrocardiographic marker for supraventricular arrhythmias, and its effect on AN. The study group included 48 patients with AN, most hospitalized for a few weeks, and a matched control group. All participants underwent 12-lead electrocardiography (ECG) under strict standards. P wave length and P wave dispersion in each patient were computed from a randomly selected beat and an averaged beat, constructed from 7 to 12 beats, included in a 10-s ECG. There were no statistically significant differences found between the groups for minimal, maximal, average P wave duration and P wave dispersion, calculated either from a random beat or averaged beats. In conclusion, medically treated AN patients who have gained weight have normal P wave parameters, and therefore do not appear to have an increased electrocardiographic risk for atrial fibrillation compared with healthy controls. Further studies are required to evaluate the influence of different disease stages, electrolyte imbalance and other medical complications on P wave parameters and risk for supraventricular arrhythmias in AN patients. PMID:22421068

  14. Anomalous incident-angle and elliptical-polarization rotation of an elastically refracted P-wave

    PubMed Central

    Fa, Lin; Fa, Yuxiao; Zhang, Yandong; Ding, Pengfei; Gong, Jiamin; Li, Guohui; Li, Lijun; Tang, Shaojie; Zhao, Meishan

    2015-01-01

    We report a newly discovered anomalous incident-angle of an elastically refracted P-wave, arising from a P-wave impinging on an interface between two VTI media with strong anisotropy. This anomalous incident-angle is found to be located in the post-critical incident-angle region corresponding to a refracted P-wave. Invoking Snell’s law for a refracted P-wave provides two distinctive solutions before and after the anomalous incident-angle. For an inhomogeneously refracted and elliptically polarized P-wave at the anomalous incident-angle, its rotational direction experiences an acute variation, from left-hand elliptical to right-hand elliptical polarization. The new findings provide us an enhanced understanding of acoustical-wave scattering and lead potentially to widespread and novel applications. PMID:26244284

  15. Acousto-ultrasonic input-output characterization of unidirectional fiber composite plate by P waves

    NASA Technical Reports Server (NTRS)

    Liao, Peter; Williams, James H., Jr.

    1988-01-01

    The single reflection problem for an incident P wave at a stress free plane boundary in a semi-infinite transversely isotropic medium whose isotropic plane is parallel to the plane boundary is analyzed. It is found that an obliquely incident P wave results in a reflected P wave and a reflected SV wave. The delay time for propagation between the transmitting and the receiving transducers is computed as if the P waves were propagating in an infinite half space. The displacements associated with the P waves in the plate and which may be detected by a noncontact NDE receiving transducer are approximated by an asymptotic solution for an infinite transversely isotropic medium subjected to a harmonic point load.

  16. Bosonization of Weyl Fermions

    NASA Astrophysics Data System (ADS)

    Marino, Eduardo

    The electron, discovered by Thomson by the end of the nineteenth century, was the first experimentally observed particle. The Weyl fermion, though theoretically predicted since a long time, was observed in a condensed matter environment in an experiment reported only a few weeks ago. Is there any linking thread connecting the first and the last observed fermion (quasi)particles? The answer is positive. By generalizing the method known as bosonization, the first time in its full complete form, for a spacetime with 3+1 dimensions, we are able to show that both electrons and Weyl fermions can be expressed in terms of the same boson field, namely the Kalb-Ramond anti-symmetric tensor gauge field. The bosonized form of the Weyl chiral currents lead to the angle-dependent magneto-conductance behavior observed in these systems.

  17. Twisted Split Fermions

    SciTech Connect

    Grossman, Yuval; Harnik, Roni; Perez, Gilad; Schwartz, MatthewD.; Surujon, Ze'ev

    2004-07-30

    The observed flavor structure of the standard model arises naturally in ''split fermion'' models which localize fermions at different places in an extra dimension. It has, until now, been assumed that the bulk masses for such fermions can be chosen to be flavor diagonal simultaneously at every point in the extra dimension, with all the flavor violation coming from the Yukawa couplings to the Higgs. We consider the more natural possibility in which the bulk masses cannot be simultaneously diagonalized, that is, that they are twisted in flavor space. We show that, in general, this does not disturb the natural generation of hierarchies in the flavor parameters. Moreover, it is conceivable that all the flavor mixing and CP-violation in the standard model may come only from twisting, with the five-dimensional Yukawa couplings taken to be universal.

  18. Twisted Split Fermions

    SciTech Connect

    Grossman, Y

    2004-07-24

    The observed flavor structure of the standard model arises naturally in ''split fermion'' models which localize fermions at different places in an extra dimension. It has, until now, been assumed that the bulk masses for such fermions can be chosen to be flavor diagonal simultaneously at every point in the extra dimension, with all the flavor violation coming from the Yukawa couplings to the Higgs. We consider the more natural possibility in which the bulk masses cannot be simultaneously diagonalized, that is, that they are twisted in flavor space. We show that, in general, this does not disturb the natural generation of hierarchies in the flavor parameters. Moreover, it is conceivable that all the flavor mixing and CP-violation in the standard model may come only from twisting, with the five-dimensional Yukawa couplings taken to be universal.

  19. A novel T wave cancellation method based on MAP estimation for P wave extraction.

    PubMed

    Wei, Chang-An; Dai, Huhe

    2015-01-01

    P wave and T wave in human-body electrocardiogram (ECG) signals often fuse together when atrial premature contract (APC) occurs. P waves within the fused signals are valuable for the measurement of P wave parameters as well as diagnosis of supra-ventricular arrhythmias. However, the problem of extracting P wave from the fused signals is seldom addressed. In this study, a novel T wave cancellation method for P wave extraction based on maximum a posteriori (MAP) estimation is proposed. In order to accurately cancel the T wave within the fused signal, T wave and the timing point of T wave peak are estimated simultaneously. The estimated timing point of T wave peak is used as alignment reference point for T wave subtraction. Simulation results show that the proposed method outperform the traditional T wave cancellation method in terms of both normalized mean square error and cross-correlation index. The results for real ECGs with APC demonstrate that the extracted P waves using the proposed method are more similar to the non-overlapping P waves in terms of morphology than the ones using the traditional T wave cancellation method. PMID:26405921

  20. Complex seismic amplitude inversion for P-wave and S-wave quality factors

    NASA Astrophysics Data System (ADS)

    Zong, Zhaoyun; Yin, Xingyao; Wu, Guochen

    2015-07-01

    Stratum quality factors (P-wave and S-wave quality factors, Qp and Qs) have gradually been utilized in the study of physical state of crust and uppermost mantle, tectonic evolution, hydrogeololgy, gas hydrates, petroleum exploration, etc. Different opinions of the seismic attenuation mechanism result in various approaches to estimate the P-wave and S-wave quality factors. Considering the viscoelasticity of the underground medium, the constitutive matrix of the Earth medium is written as the superposition of homogeneous background medium, elastic perturbation medium and viscoelastic perturbation medium. Under the hypothesis of Born integral and stationary phase approximation, the seismic reflectivity is initially raised in terms of P-wave and S-wave moduli, density, P-wave and S-wave quality factors. Furthermore, incorporating the complex seismic traces with the seismic wavelets at different offsets, a two-step inversion approach is proposed to estimate the P-wave and S-wave quality factors. The AVO/AVA Bayesian inversion approach is suggested to estimate the P-wave modulus and S-wave modulus with the real component of the pre-stack seismic data initially. Taking the estimated P-wave and S-wave moduli as prior information, the P-wave and S-wave quality factors are further estimated with the imaginary component of the complex pre-stack seismic data, which is the quadrature of the original data. Finally, synthetic examples demonstrate that the proposed approach is able to estimate P-wave and S-wave quality factors stably and properly, and two field data examples demonstrate that the proposed approach may work as an efficient approach to fluid identification.

  1. Tests of constituent-quark generation methods which maintain both the nucleon center of mass and the desired radial distribution in Monte Carlo Glauber models

    NASA Astrophysics Data System (ADS)

    Mitchell, J. T.; Perepelitsa, D. V.; Tannenbaum, M. J.; Stankus, P. W.

    2016-05-01

    Several methods of generating three constituent quarks in a nucleon are evaluated which explicitly maintain the nucleon's center of mass and desired radial distribution and can be used within Monte Carlo Glauber frameworks. The geometric models provided by each method are used to generate distributions over the number of constituent quark participants (Nqp) in p +p ,d +Au , and Au +Au collisions. The results are compared with each other and to a previous result of Nqp calculations, without this explicit constraint, used in measurements of √{sNN}=200 GeV p +p ,d +Au , and Au +Au collisions at the BNL Relativistic Heavy Ion Collider.

  2. Preliminary design report of a relativistic-Klystron two-beam-accelerator based power source for a 1 TeV center-of-mass next linear collider

    SciTech Connect

    Yu, S.; Goffeney, N.; Henestroza, E.

    1995-02-22

    A preliminary point design for an 11.4 GHz power source for a 1 TeV center-of-mass Next Linear Collider (NLC) based on the Relativistic-Klystron Two-Beam-Accelerator (RK-TBA) concept is presented. The present report is the result of a joint LBL-LLNL systems study. consisting of three major thrust areas: physics, engineering, and costing. The new RK-TBA point design, together with our findings in each of these areas, are reported.

  3. p{sub x}+ip{sub y} Superfluid from s-Wave Interactions of Fermionic Cold Atoms

    SciTech Connect

    Zhang Chuanwei; Tewari, Sumanta; Lutchyn, Roman M.; Das Sarma, S.

    2008-10-17

    Two-dimensional (p{sub x}+ip{sub y}) superfluids or superconductors offer a playground for studying intriguing physics such as quantum teleportation, non-Abelian statistics, and topological quantum computation. Creating such a superfluid in cold fermionic atom optical traps using p-wave Feshbach resonance is turning out to be challenging. Here we propose a method to create a p{sub x}+ip{sub y} superfluid directly from an s-wave interaction making use of a topological Berry phase, which can be artificially generated. We discuss ways to detect the spontaneous Hall mass current, which acts as a diagnostic for the chiral p-wave superfluid.

  4. Explanation of observable secular variations of gravity and alternative methods of determination of drift of the center of mass of the Earth

    NASA Astrophysics Data System (ADS)

    Barkin, Yury

    2010-05-01

    The summary. On the basis of geodynamic model of the forced relative displacement of the centers of mass of the core and the mantle of the Earth the secular variations of a gravity and heights of some gravimetry stations on a surface of the Earth have ben studied. At the account of secular drift of the center of mass of the Earth which on our geodynamic model is caused by the unidirectional drift of the core of the Earth relatively to the mantle, the full explanation is given to observable secular variations of a gravity at stations Ny-Alesund (Norway), Churchill (Canada), Medicine (Italy), Sayowa (Antarctica), Strastburg (France), Membach (Belgium), Wuhan (China) and Metsahovi (Finland). Two new methods of determination of secular drift of the center of mass of the Earth, alternative to classical method of a space geodesy are offered: 1) on the basis of gravimetry data about secular trends of a gravity at the stations located on all basic regions of the Earth; 2) on the basis of the comparative analysis of altimetry and coastal data about secular changes of sea level also in basic regions of ocean. 1. Secular drift of the center of mass of the core and the center of mass of the Earth. A secular drift of the center of mass of the Earth to the North relatively to special center O on an axis of rotation of the Earth for which the coefficient of third zonal harmonic J3' = 0, has been predicted in the author work [1]. A drift in a direction to a geographical point (pole P) 70°0 N and 104°3 E has been established for the first time theoretically - as a result of the analysis of the global directed redistribution of masses of the Earth, explaining the observed secular drift of the pole of an axis of rotation of the Earth and not tidal acceleration of its axial rotation [2]. In [1] velocity of drift it has been estimated in 1-2 cm/yr. For specified center O the figure of a planet is as though deprived of pure-shaped form (J3' = 0). And in this sense the point O can be

  5. Increased P-wave dispersion a risk for atrial fibrillation in adolescents with anorexia nervosa.

    PubMed

    Ertuğrul, İlker; Akgül, Sinem; Derman, Orhan; Karagöz, Tevfik; Kanbur, Nuray

    2016-01-01

    Studies have shown that a prolonged P-wave dispersion is a risk factor for the development of atrial fibrillation. The aim of this study was to evaluate P-wave dispersion in adolescents with anorexia nervosa at diagnosis. We evaluated electrocardiographic findings, particularly the P-wave dispersion, at initial assessment in 47 adolescents with anorexia nervosa. Comparison of P-wave dispersion between adolescents with anorexia nervosa and controls showed a statistically significant higher P-wave dispersion in patients with anorexia nervosa (72 ± 16.3 msec) when compared to the control group (43.8 ± 9.5 msec). Percent of body weight lost, lower body mass index, and higher weight loss rate in the patients with anorexia nervosa had no effect on P-wave dispersion. Due to the fact that anorexia nervosa has a high mortality rate we believe that cardiac pathologies such as atrial fibrillation must also be considered in the medical evaluation. PMID:25985103

  6. Experimental study of the stress effect on attenuation of normally incident P-wave through coal

    NASA Astrophysics Data System (ADS)

    Feng, Junjun; Wang, Enyuan; Chen, Liang; Li, Xuelong; Xu, Zhaoyong; Li, Guoai

    2016-09-01

    The purpose of this study is to experimentally investigate the stress effect on normally incident P-wave attenuation through coal specimens. Laboratory tests were carried out using a Split Hopkinson pressure bar (SHPB) system, and a modified method was proposed to determine the quality factor (Q) of P-waves through coal specimens. Larger quality factor denotes less energy attenuated during P-wave propagating through coal. Experimental results indicate that the quality factor and stress (σ) within coal specimens are positively correlated. The P-wave propagation through coal specimens causes crack closure at the beginning of the coal fracture process in SHPB tests, an innovative model was thus proposed to describe the relationship between the crack closure length and the dynamic stress induced by P-wave. Finally, the stress effect on P-wave attenuation through coal was quantitatively represented by a power function Q = a(c-bσ)- 6, and the material constants a, b, and c were determined as 1.227, 1.314, and 0.005, respectively. The results obtained in this study would be helpful for engineers to estimate seismic energy attenuation and coal mass instability in coal mines.

  7. Contact Tensor in a p-Wave Fermi Gas with Anisotropic Feshbach Resonances

    NASA Astrophysics Data System (ADS)

    Yoshida, Shuhei M.; Ueda, Masahito

    2016-05-01

    Recent theoretical and experimental investigations have revealed that a Fermi gas with a p-wave Feshbach resonance has universal relations between the system's high-momentum behavior and thermodynamics. A new feature introduced by the p-wave interaction is anisotropy in the Feshbach resonances; three degenerate p-wave resonances split according to the magnetic quantum number of the closed-channel molecules | m | due to the magnetic dipole-dipole interaction. Here, we investigate the consequences of the anisotropy. We show that the momentum distribution has a high-momentum asymptote nk ~k-2 ∑ m, m' = - 1 1 >Cm, m'Y1m * (\\kcirc)Y1m' (\\kcirc) , in which we introduce the p-wave contact tensor Cm ,m'. In contrast to the previous studies, it has nine components. We identify them as the number, angular momentum, and nematicity of the closed-channel molecules. We also discuss two examples, the anisotropic p-wave superfluid and a gas confined in a cigar-shaped trap, which exhibit a nematicity component in the p-wave contact tensor.

  8. Measurements of the reaction e/+/e/-/ yielding gamma-gamma at center-of-mass energies in the range 6.2-7.4 GeV

    NASA Technical Reports Server (NTRS)

    Hilger, E.; Beron, B. L.; Carrington, R. L.; Ford, R. L.; Hill, W. T.; Hofstadter, R.; Hughes, E. B.; Liberman, A. D.; Martin, T. W.; Oneill, L. H.

    1977-01-01

    The cross section for the pair-annihilation reaction e(+)e(-) yields gamma-gamma were measured at center-of-mass energies in the range 6.2-7.4 GeV and at production angles close to 90 deg. The experimental apparatus consisted of two identical spectrometers which were set to view the luminous region at SPEAR-II from opposite directions at an azimuthal angle of 45 deg. In each spectrometer there was a NaI(TI) crystal 20 radiation lengths thick and 30 in. in diameter to measure the gamma-ray energies. Annihilation events were detected by an electronic trigger which required only the observation in coincidence of more than 0.2 GeV in each NaI(TI) crystal within + or - 15 nsec of the crossing beams. The observed rates of pair-annihilation events were found to be in agreement with those expected from quantum electrodynamics (QED) at all the center-of-mass energies used.

  9. Biphasic P wave in inferior leads and the development of atrial fibrillation

    PubMed Central

    Hayashi, Hideki; Horie, Minoru

    2015-01-01

    Background Anisotropic and slow conduction in the atrium underlie the development of atrial fibrillation (AF). This study aimed to investigate the P wave characteristics associated with the development of AF in patients with a biphasic P wave in the inferior leads. Methods Digital analysis of retrospectively recorded 12-lead electrocardiograms was performed to select patients with a biphasic P wave (positive/negative) in lead II from a database of 114,334 patients. Characteristics of the P wave in the inferior leads associated with incidence of AF were determined. Receiver operating characteristic curves dichotomized P wave variables were measured in each lead. Results A total of 141 patients (77 men; mean age, 64±19 years) were enrolled in this study. Twenty-nine (20.6%) patients developed AF (AF group) vs. 112 (79.6%) who did not (non-AF group) during a follow-up period of 50±62 months. The amplitude of the initial P wave portion in lead II was significantly larger in the AF group when compared with the non-AF group (77.3±77.0 µV vs. 51.0±30.1 µV, p=0.003), while the amplitude of the terminal P wave portion in lead III was significantly decreased in the AF group when compared with the non-AF group (−70.6±41.3 µV vs. −89.1±38.1 µV, p=0.024). The duration of the initial P wave portion in lead III was significantly longer in the AF group when compared with the non-AF group (52.7±34.6 ms vs. 35.8±30.4 ms, p=0.011). Multivariate Cox proportional-hazards analysis confirmed that the increased duration of the initial P wave portion in lead III (≥71 ms) was independently associated with AF development (hazard ratio 2.90, 95% confidence interval 1.16–7.11, p=0.02). Conclusion The analyses of the biphasic P wave in the inferior leads suggest that the development of AF could be attributed to increased atrial slow conduction. PMID:26702318

  10. Evaluation of the P Wave Axis in Patients With Systemic Lupus Erythematosus

    PubMed Central

    Acar, Rezzan Deniz; Bulut, Mustafa; Acar, Şencan; Izci, Servet; Fidan, Serdar; Yesin, Mahmut; Efe, Suleyman Cagan

    2015-01-01

    Introduction: P wave axis is one of the most practical clinical tool for evaluation of cardiovascular disease. The aim of our study was to evaluate the P wave axis in electrocardiogram (ECG), left atrial function and association between the disease activity score in patients with systemic lupus erythematosus (SLE). Methods: Standard 12-lead surface ECGs were recorded by at a paper speed of 25 m/s and an amplifier gain of 10 mm/mV. The heart rate (HR), the duration of PR, QRS, QTd (dispersion), the axis of P wave were measured by ECG machine automatically. Results: The P wave axis was significantly increased in patients with SLE (49 ± 20 vs. 40 ± 18, P = 0.037) and the disease activity score was found positively correlated with P wave axis (r: 0.382, P = 0.011). The LA volume and the peak systolic strain of the left atrium (LA) were statistically different between the groups (P = 0.024 and P = 0.000). The parameters of the diastolic function; E/A and E/e’ were better in the control group than the patients with SLE (1.1 ± 0.3 vs. 1.3 ± 0.3, P = 0.041 and 6.6 ± 2.8 vs. 5.4 ± 1.4, P = 0.036, respectively). Conclusion: P wave axis was found significantly increased in patients with SLE and positively correlated with SELENA-SLEDAI score. As the risk score increases in patients with SLE, P wave axis changes which may predict the risk of all-cause and cardiovascular mortality. PMID:26702344

  11. Scattering amplitude of ultracold atoms near the p-wave magnetic Feshbach resonance

    SciTech Connect

    Zhang Peng; Naidon, Pascal; Ueda, Masahito

    2010-12-15

    Most of the current theories on the p-wave superfluid in cold atomic gases are based on the effective-range theory for the two-body scattering, where the low-energy p-wave scattering amplitude f{sub 1}(k) is given by f{sub 1}(k)=-1/[ik+1/(Vk{sup 2})+1/R]. Here k is the incident momentum, V and R are the k-independent scattering volume and effective range, respectively. However, due to the long-range nature of the van der Waals interaction between two colliding ultracold atoms, the p-wave scattering amplitude of the two atoms is not described by the effective-range theory [J. Math. Phys. 4, 54 (1963); Phys. Rev. A 58, 4222 (1998)]. In this paper we provide an explicit calculation for the p-wave scattering of two ultracold atoms near the p-wave magnetic Feshbach resonance. We show that in this case the low-energy p-wave scattering amplitude f{sub 1}(k)=-1/[ik+1/(V{sup eff}k{sup 2})+1/(S{sup eff}k)+1/R{sup eff}] where V{sup eff}, S{sup eff}, and R{sup eff} are k-dependent parameters. Based on this result, we identify sufficient conditions for the effective-range theory to be a good approximation of the exact scattering amplitude. Using these conditions we show that the effective-range theory is a good approximation for the p-wave scattering in the ultracold gases of {sup 6}Li and {sup 40}K when the scattering volume is enhanced by the resonance.

  12. Hadron Properties with FLIC Fermions

    SciTech Connect

    James Zanotti; Wolodymyr Melnitchouk; Anthony Williams; J Zhang

    2003-07-01

    The Fat-Link Irrelevant Clover (FLIC) fermion action provides a new form of nonperturbative O(a)-improvement in lattice fermion actions offering near continuum results at finite lattice spacing. It provides computationally inexpensive access to the light quark mass regime of QCD where chiral nonanalytic behavior associated with Goldstone bosons is revealed. The motivation and formulation of FLIC fermions, its excellent scaling properties and its low-lying hadron mass phenomenology are presented.

  13. Evidence for universal relations describing a gas with p-wave interactions

    NASA Astrophysics Data System (ADS)

    Luciuk, Christopher; Trotzky, Stefan; Smale, Scott; Yu, Zhenhua; Zhang, Shizhong; Thywissen, Joseph H.

    2016-06-01

    In dilute gases, a set of universal relations, known as the contact relations, directly connects thermodynamics and microscopic properties. So far, they have been established only for interactions with s-wave symmetry--that is, without relative angular momentum. Here we report measurements of two new physical quantities, the p-wave contacts, and, using recently proposed relations, present evidence that they encode the universal aspects of p-wave interactions. Our experiments use an ultracold Fermi gas of 40K, in which s-wave interactions are suppressed by polarizing the sample, whereas p-wave interactions are enhanced by working near a scattering resonance. Using time-resolved spectroscopy, we study how correlations in the system develop after quenching the atoms into an interacting state. By combining quasi-steady-state measurements with new contact relations, we infer an attractive p-wave interaction energy as large as half the Fermi energy. Our results reveal new ways to understand and characterize the properties of a resonant p-wave quantum gas.

  14. Evidence for universal relations describing a gas with p-wave interactions

    NASA Astrophysics Data System (ADS)

    Smale, S.; Luciuk, C.; Trotzky, S.; Yu, Zhenhua; Zhang, Shizhong; Thywissen, J. H.

    2016-05-01

    A remarkable set of universal relations is known to directly connect thermodynamic and microscopic properties of interacting Fermi gases. So far, these contact relations have been established only for interactions with s-wave symmetry, i.e., with zero relative angular momentum. We report measurements of two new physical quantities, the p-wave contacts, and present evidence that they encode the universal aspects of p-wave interactions through recently proposed relations. Our experiments use a spin-polarized ultracold Fermi gas of 40 K, in which s-wave interactions are suppressed, while p-wave interactions are enhanced near a Feshbach resonance. Using time-resolved spectroscopy and momentum distribution measurements, we study how correlations in the system develop after quenching the atoms into an interacting state. Combining quasi-steady-state measurements with new contact relations, we infer an attractive p-wave interaction energy as large as the Fermi energy. Our results reveal new ways to understand and characterize the properties of resonantly interacting p-wave quantum gases.

  15. What Do s- and p-Wave Neutron Average Radiative Widths Reveal

    SciTech Connect

    Mughabghab, S.F.

    2010-04-30

    A first observation of two resonance-like structures at mass numbers 92 and 112 in the average capture widths of the p-wave neutron resonances relative to the s-wave component is interpreted in terms of a spin-orbit splitting of the 3p single-particle state into P{sub 3/2} and P{sub 1/2} components at the neutron separation energy. A third structure at about A = 124, which is not correlated with the 3p-wave neutron strength function, is possibly due to the Pygmy Dipole Resonance. Five significant results emerge from this investigation: (i) The strength of the spin-orbit potential of the optical-model is determined as 5.7 {+-} 0.5 MeV, (ii) Non-statistical effects dominate the p-wave neutron-capture in the mass region A = 85 - 130, (iii) The background magnitude of the p-wave average capture-width relative to that of the s-wave is determined as 0.50 {+-} 0.05, which is accounted for quantitatively in tenns of the generalized Fermi liquid model of Mughabghab and Dunford, (iv) The p-wave resonances arc partially decoupled from the giant-dipole resonance (GDR), and (v) Gamma-ray transitions, enhanced over the predictions of the GDR, are observed in the {sup 90}Zr - {sup 98}Mo and Sn-Ba regions.

  16. The motion of a symmetric gyrostat around the center of mass in a circular orbit in the presence of viscoelastic bars and disc

    NASA Astrophysics Data System (ADS)

    El-Hafiez, S. A.; Fares, M. E.

    A symmetric gyrostat which has a homogeneous viscoelastic disk and two bars attached to it is considered. Furthermore, the gyrostat has a rotor oriented inside it such that the rotor is statically and dynamically balanced. This system has a rotational motion around its center of mass in a circular orbit under a central gravitational field. Bending vibrations of the bars and the disk are accompanied by dissipation of energy, which is the cause of the evolution of the system's rotational motion. Using the method of separation of motion and averaging, the approximate equations describing the evolution of rotational motion in terms of Andoyer canonical variables are obtained. The stationary motions for the system are deduced, together with the conditions of its stability.

  17. Probing Higgs boson self-interactions in proton-proton collisions at a center-of-mass energy of 100 TeV

    NASA Astrophysics Data System (ADS)

    Fuks, Benjamin; Kim, Jeong Han; Lee, Seung J.

    2016-02-01

    We present a phenomenological study of triple-Higgs production in which we estimate the prospects for measuring the form of the Higgs potential at future circular collider projects. We analyze proton-proton collisions at a center-of-mass energy of 100 TeV and focus on two different signatures in which the final state is made of four b jets and either a pair of photons or a pair of tau leptons. We study the resulting sensitivity on the Higgs cubic and quartic self-interactions and investigate how it depends on the b -tagging, tau-tagging and photon-resolution performances of detectors that could be designed for these future machines. We then discuss possible luminosity goals for future 100 TeV collider projects that would allow for a measurement of the Higgs potential and its possible departures from the Standard Model expectation.

  18. Measurement of the photon-proton total cross section at a center-of-mass energy of 209 GeV at HERA

    NASA Astrophysics Data System (ADS)

    Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Aghuzumtsyan, G.; Bartsch, D.; Brock, I.; Crittenden, J.; Goers, S.; Hartmann, H.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Kind, O.; Paul, E.; Rautenberg, J.; Renner, R.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Wessoleck, H.; Bailey, D. S.; Brook, N. H.; Cole, J. E.; Foster, B.; Heath, G. P.; Heath, H. F.; Robins, S.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Wing, M.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Helbich, M.; Liu, X.; Mellado, B.; Paganis, S.; Schmidke, W. B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Olkiewicz, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Grabowska-Bold, I.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowal, M.; Kowalski, T.; Mindur, B.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Szuba, D.; Szuba, J.; Kotański, A.; Słomiński, W.; Bauerdick, L. A. T.; Behrens, U.; Borras, K.; Chiochia, V.; Dannheim, D.; Desler, K.; Drews, G.; Fourletova, J.; Fox-Murphy, A.; Fricke, U.; Geiser, A.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hillert, S.; Kötz, U.; Kowalski, H.; Labes, H.; Lelas, D.; Löhr, B.; Mankel, R.; Martens, J.; Martínez, M.; Moritz, M.; Notz, D.; Petrucci, M. C.; Polini, A.; Schneekloth, U.; Selonke, F.; Stonjek, S.; Surrow, B.; Whitmore, J. J.; Wichmann, R.; Wolf, G.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Genta, C.; Pelfer, P. G.; Bamberger, A.; Benen, A.; Coppola, N.; Markun, P.; Raach, H.; Wölfle, S.; Bell, M.; Bussey, P. J.; Doyle, A. T.; Glasman, C.; Hanlon, S.; Lee, S. W.; Lupi, A.; McCance, G. J.; Saxon, D. H.; Skillicorn, I. O.; Bodmann, B.; Holm, U.; Salehi, H.; Wick, K.; Ziegler, A.; Ziegler, Ar.; Carli, T.; Gialas, I.; Klimek, K.; Lohrmann, E.; Milite, M.; Collins-Tooth, C.; Foudas, C.; Gonçalo, R.; Long, K. R.; Metlica, F.; Miller, D. B.; Tapper, A. D.; Walker, R.; Cloth, P.; Filges, D.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A. N.; Boos, E. G.; Pokrovskiy, N. S.; Zhautykov, B. O.; Ahn, S. H.; Lee, S. B.; Park, S. K.; Lim, H.; Son, D.; Barreiro, F.; García, G.; González, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Vázquez, M.; Barbi, M.; Bertolin, A.; Corriveau, F.; Ochs, A.; Padhi, S.; Stairs, D. G.; St-Laurent, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, P.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Golubkov, Yu. A.; Katkov, I. I.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Levchenko, B. B.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Vlasov, N. N.; Zotkin, S. A.; Bokel, C.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Maddox, E.; Schagen, S.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Wiggers, L.; de Wolf, E.; Brümmer, N.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Ferrando, J.; Matsushita, T.; Rigby, M.; Ruske, O.; Sutton, M. R.; Walczak, R.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Garfagnini, A.; Limentani, S.; Longhin, A.; Parenti, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Oh, B. Y.; Saull, P. R. B.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Heusch, C.; Park, I. H.; Pavel, N.; Abramowicz, H.; Dagan, S.; Gabareen, A.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J. M.; Gwenlan, C.; Hall-Wilton, R.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; Lightwood, M. S.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Smalska, B.; Sztuk, J.; Tymieniecka, T.; Ukleja, A.; Ukleja, J.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Plucinski, P.; Eisenberg, Y.; Gladilin, L. K.; Hochman, D.; Karshon, U.; Breitweg, J.; Chapin, D.; Cross, R.; Kçira, D.; Lammers, S.; Reeder, D. D.; Savin, A. A.; Smith, W. H.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Straub, P. B.; Bhadra, S.; Catterall, C. D.; Fourletov, S.; Menary, S.; Soares, M.; Standage, J.; ZEUS Collaboration

    2002-04-01

    The photon-proton total cross section has been measured in the process e+p→ e+γp→ e+X with the ZEUS detector at HERA. Events were collected with photon virtuality Q2<0.02 GeV 2 and average γp center-of-mass energy Wγp=209 GeV in a dedicated run, designed to control systematic effects, with an integrated luminosity of 49 nb -1. The measured total cross section is σtotγp=174±1 (stat.)±13 (syst.) μb. The energy dependence of the cross section is compatible with parameterizations of high-energy pp and p p¯ data.

  19. Measurement of the photon-proton total cross section at a center-of-mass energy of 209 GeV at HERA

    NASA Astrophysics Data System (ADS)

    ZEUS Collaboration; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Aghuzumtsyan, G.; Bartsch, D.; Brock, I.; Crittenden, J.; Goers, S.; Hartmann, H.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Kind, O.; Paul, E.; Rautenberg, J.; Renner, R.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Wessoleck, H.; Bailey, D. S.; Brook, N. H.; Cole, J. E.; Foster, B.; Heath, G. P.; Heath, H. F.; Robins, S.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Wing, M.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Helbich, M.; Liu, X.; Mellado, B.; Paganis, S.; Schmidke, W. B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Olkiewicz, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Grabowska-Bold, I.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowal, M.; Kowalski, T.; Mindur, B.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Szuba, D.; Szuba, J.; Kotański, A.; Slomiński, W.; Bauerdick, L. A. T.; Behrens, U.; Borras, K.; Chiochia, V.; Dannheim, D.; Desler, K.; Drews, G.; Fourletova, J.; Fox-Murphy, A.; Fricke, U.; Geiser, A.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hillert, S.; Kötz, U.; Kowalski, H.; Labes, H.; Lelas, D.; Löhr, B.; Mankel, R.; Martens, J.; Martínez, M.; Moritz, M.; Notz, D.; Petrucci, M. C.; Polini, A.; Schneekloth, U.; Selonke, F.; Stonjek, S.; Surrow, B.; Whitmore, J. J.; Wichmann, R.; Wolf, G.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Genta, C.; Pelfer, P. G.; Bamberger, A.; Benen, A.; Coppola, N.; Markun, P.; Raach, H.; Wölfle, S.; Bell, M.; Bussey, P. J.; Doyle, A. T.; Glasman, C.; Hanlon, S.; Lee, S. W.; Lupi, A.; McCance, G. J.; Saxon, D. H.; Skillicorn, I. O.; Bodmann, B.; Holm, U.; Salehi, H.; Wick, K.; Ziegler, A.; Ziegler, Ar.; Carli, T.; Gialas, I.; Klimek, K.; Lohrmann, E.; Milite, M.; Collins-Tooth, C.; Foudas, C.; Gonçalo, R.; Long, K. R.; Metlica, F.; Miller, D. B.; Tapper, A. D.; Walker, R.; Cloth, P.; Filges, D.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A. N.; Boos, E. G.; Pokrovskiy, N. S.; Zhautykov, B. O.; Ahn, S. H.; Lee, S. B.; Park, S. K.; Lim, H.; Son, D.; Barreiro, F.; García, G.; González, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Vázquez, M.; Barbi, M.; Bertolin, A.; Corriveau, F.; Ochs, A.; Padhi, S.; Stairs, D. G.; St-Laurent, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, P.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Golubkov, Yu. A.; Katkov, I. I.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Levchenko, B. B.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Vlasov, N. N.; Zotkin, S. A.; Bokel, C.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Maddox, E.; Schagen, S.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Wiggers, L.; de Wolf, E.; Brümmer, N.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Ferrando, J.; Matsushita, T.; Rigby, M.; Ruske, O.; Sutton, M. R.; Walczak, R.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Garfagnini, A.; Limentani, S.; Longhin, A.; Parenti, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Oh, B. Y.; Saull, P. R. B.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Heusch, C.; Park, I. H.; Pavel, N.; Abramowicz, H.; Dagan, S.; Gabareen, A.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J. M.; Gwenlan, C.; Hall-Wilton, R.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; Lightwood, M. S.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Smalska, B.; Sztuk, J.; Tymieniecka, T.; Ukleja, A.; Ukleja, J.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Plucinski, P.; Eisenberg, Y.; Gladilin, L. K.; Hochman, D.; Karshon, U.; Breitweg, J.; Chapin, D.; Cross, R.; Kçira, D.; Lammers, S.; Reeder, D. D.; Savin, A. A.; Smith, W. H.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Straub, P. B.; Bhadra, S.; Catterall, C. D.; Fourletov, S.; Menary, S.; Soares, M.; Standage, J.

    2002-04-01

    The photon-proton total cross section has been measured in the process e+p-->e+γp-->e+X with the ZEUS detector at HERA. Events were collected with photon virtuality Q2<0.02 GeV2 and average /γp center-of-mass energy Wγp=209 GeV in a dedicated run, designed to control systematic effects, with an integrated luminosity of 49 nb-1. The measured total cross section is σtotγp=174+/-1 (stat.)+/-13 (syst.) μb. The energy dependence of the cross section is compatible with parameterizations of high-energy /pp and /pp¯ data.

  20. Classical states of an electric dipole in an external magnetic field: Complete solution for the center of mass and trapped states

    SciTech Connect

    Atenas, Boris; Pino, Luis A. del; Curilef, Sergio

    2014-11-15

    We study the classical behavior of an electric dipole in the presence of a uniform magnetic field. Using the Lagrangian formulation, we obtain the equations of motion, whose solutions are represented in terms of Jacobi functions. We also identify two constants of motion, namely, the energy E and a pseudomomentumC{sup →}. We obtain a relation between the constants that allows us to suggest the existence of a type of bound states without turning points, which are called trapped states. These results are consistent with and complementary to previous results. - Highlights: • Bound states without turning points. • Lagrangian Formulation for an electric dipole in a magnetic field. • Motion of the center of mass and trapped states. • Constants of motion: pseudomomentum and energy.

  1. And Yet it Moves: The Dangers of Artificially Fixing the Milky Way Center of Mass in the Presence of a Massive Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Gómez, Facundo A.; Besla, Gurtina; Carpintero, Daniel D.; Villalobos, Álvaro; O'Shea, Brian W.; Bell, Eric F.

    2015-04-01

    Motivated by recent studies suggesting that the Large Magellanic Cloud (LMC) could be significantly more massive than previously thought, we explore whether the approximation of an inertial Galactocentric reference frame is still valid in the presence of such a massive LMC. We find that previous estimates of the LMC’s orbital period and apocentric distance derived assuming a fixed Milky Way (MW) are significantly shortened for models where the MW is allowed to move freely in response to the gravitational pull of the LMC. Holding other parameters fixed, the fraction of models favoring first infall is reduced. Due to this interaction, the MW center of mass within the inner 50 kpc can be significantly displaced in phase-space in a very short period of time that ranges from 0.3 to 0.5 Gyr by as much as 30 kpc and 75 km s-1. Furthermore, we show that the gravitational pull of the LMC and response of the MW are likely to significantly affect the orbit and phase space distribution of tidal debris from the Sagittarius dwarf galaxy (Sgr). Such effects are larger than previous estimates based on the torque of the LMC alone. As a result, Sgr deposits debris in regions of the sky that are not aligned with the present-day Sgr orbital plane. In addition, we find that properly accounting for the movement of the MW around its common center of mass with the LMC significantly modifies the angular distance between apocenters and tilts its orbital pole, alleviating tensions between previous models and observations. While these models are preliminary in nature, they highlight the central importance of accounting for the mutual gravitational interaction between the MW and LMC when modeling the kinematics of objects in the MW and Local Group.

  2. Study of e(+)e(-)→ωχ(cJ) at center of mass energies from 4.21 to 4.42 GeV.

    PubMed

    Ablikim, M; Achasov, M N; Ai, X C; Albayrak, O; Albrecht, M; Ambrose, D J; Amoroso, A; An, F F; An, Q; Bai, J Z; Ferroli, R Baldini; Ban, Y; Bennett, D W; Bennett, J V; Bertani, M; Bettoni, D; Bian, J M; Bianchi, F; Boger, E; Bondarenko, O; Boyko, I; Briere, R A; Cai, H; Cai, X; Cakir, O; Calcaterra, A; Cao, G F; Cetin, S A; Chang, J F; Chelkov, G; Chen, G; Chen, H S; Chen, H Y; Chen, J C; Chen, M L; Chen, S J; Chen, X; Chen, X R; Chen, Y B; Cheng, H P; Chu, X K; Chu, Y P; Cibinetto, G; Cronin-Hennessy, D; Dai, H L; Dai, J P; Dedovich, D; Deng, Z Y; Denig, A; Denysenko, I; Destefanis, M; De Mori, F; Ding, Y; Dong, C; Dong, J; Dong, L Y; Dong, M Y; Du, S X; Duan, P F; Fan, J Z; Fang, J; Fang, S S; Fang, X; Fang, Y; Fava, L; Feldbauer, F; Felici, G; Feng, C Q; Fioravanti, E; Fu, C D; Gao, Q; Gao, Y; Garzia, I; Goetzen, K; Gong, W X; Gradl, W; Greco, M; Gu, M H; Gu, Y T; Guan, Y H; Guo, A Q; Guo, L B; Guo, T; Guo, Y; Guo, Y P; Haddadi, Z; Hafner, A; Han, S; Han, Y L; Harris, F A; He, K L; He, Z Y; Held, T; Heng, Y K; Hou, Z L; Hu, C; Hu, H M; Hu, J F; Hu, T; Hu, Y; Huang, G M; Huang, G S; Huang, H P; Huang, J S; Huang, X T; Huang, Y; Hussain, T; Ji, Q; Ji, Q P; Ji, X B; Ji, X L; Jiang, L L; Jiang, L W; Jiang, X S; Jiao, J B; Jiao, Z; Jin, D P; Jin, S; Johansson, T; Julin, A; Kalantar-Nayestanaki, N; Kang, X L; Kang, X S; Kavatsyuk, M; Ke, B C; Kliemt, R; Kloss, B; Kolcu, O B; Kopf, B; Kornicer, M; Kuehn, W; Kupsc, A; Lai, W; Lange, J S; Lara, M; Larin, P; Li, Cheng; Li, C H; Li, D M; Li, F; Li, G; Li, H B; Li, J C; Li, Jin; Li, K; Li, K; Li, P R; Li, T; Li, W D; Li, W G; Li, X L; Li, X M; Li, X N; Li, X Q; Li, Z B; Liang, H; Liang, Y F; Liang, Y T; Liao, G R; Lin, D X; Liu, B J; Liu, C L; Liu, C X; Liu, F H; Liu, Fang; Liu, Feng; Liu, H B; Liu, H H; Liu, H H; Liu, H M; Liu, J; Liu, J P; Liu, J Y; Liu, K; Liu, K Y; Liu, L D; Liu, Q; Liu, S B; Liu, X; Liu, X X; Liu, Y B; Liu, Z A; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H; Lou, X C; Lu, H J; Lu, J G; Lu, R Q; Lu, Y; Lu, Y P; Luo, C L; Luo, M X; Luo, T; Luo, X L; Lv, M; Lyu, X R; Ma, F C; Ma, H L; Ma, L L; Ma, Q M; Ma, S; Ma, T; Ma, X N; Ma, X Y; Maas, F E; Maggiora, M; Malik, Q A; Mao, Y J; Mao, Z P; Marcello, S; Messchendorp, J G; Min, J; Min, T J; Mitchell, R E; Mo, X H; Mo, Y J; Moeini, H; Morales, C Morales; Moriya, K; Muchnoi, N Yu; Muramatsu, H; Nefedov, Y; Nerling, F; Nikolaev, I B; Ning, Z; Nisar, S; Niu, S L; Niu, X Y; Olsen, S L; Ouyang, Q; Pacetti, S; Patteri, P; Pelizaeus, M; Peng, H P; Peters, K; Ping, J L; Ping, R G; Poling, R; Pu, Y N; Qi, M; Qian, S; Qiao, C F; Qin, L Q; Qin, N; Qin, X S; Qin, Y; Qin, Z H; Qiu, J F; Rashid, K H; Redmer, C F; Ren, H L; Ripka, M; Rong, G; Ruan, X D; Santoro, V; Sarantsev, A; Savrié, M; Schoenning, K; Schumann, S; Shan, W; Shao, M; Shen, C P; Shen, P X; Shen, X Y; Sheng, H Y; Shepherd, M R; Song, W M; Song, X Y; Sosio, S; Spataro, S; Spruck, B; Sun, G X; Sun, J F; Sun, S S; Sun, Y J; Sun, Y Z; Sun, Z J; Sun, Z T; Tang, C J; Tang, X; Tapan, I; Thorndike, E H; Tiemens, M; Toth, D; Ullrich, M; Uman, I; Varner, G S; Wang, B; Wang, B L; Wang, D; Wang, D Y; Wang, K; Wang, L L; Wang, L S; Wang, M; Wang, P; Wang, P L; Wang, Q J; Wang, S G; Wang, W; Wang, X F; Wang, Y D; Wang, Y F; Wang, Y Q; Wang, Z; Wang, Z G; Wang, Z H; Wang, Z Y; Wei, D H; Wei, J B; Weidenkaff, P; Wen, S P; Wiedner, U; Wolke, M; Wu, L H; Wu, Z; Xia, L G; Xia, Y; Xiao, D; Xiao, Z J; Xie, Y G; Xiu, Q L; Xu, G F; Xu, L; Xu, Q J; Xu, Q N; Xu, X P; Yan, L; Yan, W B; Yan, W C; Yan, Y H; Yang, H X; Yang, L; Yang, Y; Yang, Y X; Ye, H; Ye, M; Ye, M H; Yin, J H; Yu, B X; Yu, C X; Yu, H W; Yu, J S; Yuan, C Z; Yuan, W L; Yuan, Y; Yuncu, A; Zafar, A A; Zallo, A; Zeng, Y; Zhang, B X; Zhang, B Y; Zhang, C; Zhang, C C; Zhang, D H; Zhang, H H; Zhang, H Y; Zhang, J J; Zhang, J L; Zhang, J Q; Zhang, J W; Zhang, J Y; Zhang, J Z; Zhang, K; Zhang, L; Zhang, S H; Zhang, X J; Zhang, X Y; Zhang, Y; Zhang, Y H; Zhang, Z H; Zhang, Z P; Zhang, Z Y; Zhao, G; Zhao, J W; Zhao, J Y; Zhao, J Z; Zhao, Lei; Zhao, Ling; Zhao, M G; Zhao, Q; Zhao, Q W; Zhao, S J; Zhao, T C; Zhao, Y B; Zhao, Z G; Zhemchugov, A; Zheng, B; Zheng, J P; Zheng, W J; Zheng, Y H; Zhong, B; Zhou, L; Zhou, Li; Zhou, X; Zhou, X K; Zhou, X R; Zhou, X Y; Zhu, K; Zhu, K J; Zhu, S; Zhu, X L; Zhu, Y C; Zhu, Y S; Zhu, Z A; Zhuang, J; Zou, B S; Zou, J H

    2015-03-01

    Based on data samples collected with the BESIII detector at the BEPCII collider at nine center of mass energies from 4.21 to 4.42 GeV, we search for the production of e^{+}e^{-}→ωχ_{cJ} (J=0, 1, 2). The process e^{+}e^{-}→ωχ_{c0} is observed for the first time, and the Born cross sections at sqrt[s]=4.23 and 4.26 GeV are measured to be (55.4±6.0±5.9) and (23.7±5.3±3.5)  pb, respectively, where the first uncertainties are statistical and the second are systematic. The ωχ_{c0} signals at the other seven energies and the e^{+}e^{-}→ωχ_{c1} and ωχ_{c2} signals are not significant, and the upper limits on the cross sections are determined. By examining the ωχ_{c0} cross section as a function of center of mass energy, we find that it is inconsistent with the line shape of the Y(4260) observed in e^{+}e^{-}→π^{+}π^{-}J/ψ. Assuming the ωχ_{c0} signals come from a single resonance, we extract the mass and width of the resonance to be (4230±8±6)  MeV/c^{2} and (38±12±2)  MeV, respectively, and the statistical significance is more than 9σ. PMID:25793804

  3. BCS-BEC crossover and quantum hydrodynamics in p-wave superfluids with a symmetry of the A1 phase

    SciTech Connect

    Kagan, M. Yu. Efremov, D. V.

    2010-03-15

    We solve the Leggett equations for the BCS-BEC crossover in a three dimensional resonance p-wave superfluid with the symmetry of the A1 phase. We calculate the sound velocity, the normal density, and the specific heat for the BCS domain ({mu} > 0), for the BEC domain ({mu} < 0), and close to the important point {mu} = 0 in the 100% polarized case. We find the indications of a quantum phase transition close to the point {mu}(T = 0) = 0. Deep in the BCS and BEC domains, the crossover ideas of Leggett, Nozieres, and Schmitt-Rink work quite well. We discuss the spectrum of orbital waves, the paradox of intrinsic angular momentum and the complicated problem of chiral anomaly in the BCS A1 phase at T = 0. We present two different approaches to the chiral anomaly, based on supersymmetric hydrodynamics and on the formal analogy with the Dirac equation in quantum electrodynamics. We evaluate the damping of nodal fermions due to different decay processes in the superclean case at T = 0 and find that a ballistic regime {omega}{tau} >> 1 occurs. We propose to use aerogel or nonmagnetic impurities to reach the hydrodynamic regime {omega}{tau} << 1 at T = 0. We discuss the concept of the spectral flow and exact cancelations between time derivatives of anomalous and quasiparticle currents in the equation for the total linear momentum conservation. We propose to derive and solve the kinetic equation for the nodal quasiparticles in both the hydrodynamic and ballistic regimes to demonstrate this cancelation explicitly. We briefly discuss the role of the other residual interactions different from damping and invite experimentalists to measure the spectrum and damping of orbital waves in the A phase of {sup 3}He at low temperatures.

  4. Universal Relations for a Fermi Gas Close to a p -Wave Interaction Resonance

    NASA Astrophysics Data System (ADS)

    Yu, Zhenhua; Thywissen, Joseph H.; Zhang, Shizhong

    2015-09-01

    We investigate the properties of a spinless Fermi gas close to a p -wave interaction resonance. We show that the effects of interaction near a p -wave resonance are captured by two contacts, which are related to the variation of energy with the p -wave scattering volume v and with the effective range R in two adiabatic theorems. Exact pressure and virial relations are derived. We show how the two contacts determine the leading and subleading asymptotic behavior of the momentum distribution (˜1 /k2 and ˜1 /k4) and how they can be measured experimentally by radio-frequency and photoassociation spectroscopies. Finally, we evaluate the two contacts at high temperature with a virial expansion.

  5. Factors Influencing Intracavitary Electrocardiographic P-Wave Changes during Central Venous Catheter Placement.

    PubMed

    Wang, Guorong; Guo, Ling; Jiang, Bin; Huang, Min; Zhang, Jian; Qin, Ying

    2015-01-01

    Amplitude changes in the P-wave of intracavitary electrocardiography have been used to assess the tip placement of central venous catheters. The research assessed the sensitivity and specificity of this sign in comparison with standard radiographic techniques for tip location, focusing on factors influencing its clinical utility. Both intracavitary electrocardiography guided tip location and X-ray positioning were used to verify catheter tip locations in patients undergoing central venous catheter insertion. Intracavitary electrocardiograms from 1119 patients (of a total 1160 subjects) showed specific amplitude changes in the P-wave. As the results show, compared with X-ray positioning, the sensitivity of electrocardiography-guided tip location was 97.3%, with false negative rate of 2.7%; the specificity was 1, with false positive rate of zero. Univariate analyses indicated that features including age, gender, height, body weight, and heart rate have no statistically significant influence on P-wave amplitude changes (P > 0.05). Multivariate logistic regression revealed that catheter insertion routes (OR = 2.280, P = 0.003) and basal P-wave amplitude (OR = 0.553, P = 0.003) have statistically significant impacts on P-wave amplitude changes. As a reliable indicator of tip location, amplitude change in the P-wave has proved of good sensitivity and excellent specificity, and the minor, zero, false positive rate supports the clinical utility of this technique in early recognition of malpositioned tips. A better sensitivity was achieved in placement of centrally inserted central catheters (CICCs) than that of peripherally inserted central catheters (PICCs). In clinical practice, a combination of intracavitary electrocardiography, ultrasonic inspection and the anthropometric measurement method would further improve the accuracy. PMID:25915758

  6. Nucleon Resonances from FLIC Fermions

    SciTech Connect

    Derek Leinweber; J. Hedditch; Wally Melnitchouk; Anthony Williams

    2003-01-01

    The Fat Link Irrelevant Glover (FL1C) fermion action and its associated phenomenology is described. The scaling analysis indicates FLIC fermions provide a new form of nonperturbative O(a) improvement where near-continuum results are obtained at finite lattice spacing spin-1/2 and spin-3/2 , even and odd parity nucleon resonances are investigated.

  7. Finite-momentum superfluidity and phase transitions in a p-wave resonant Bose gas

    SciTech Connect

    Choi, Sungsoo; Radzihovsky, Leo

    2011-10-15

    We study a degenerate two-species gas of bosonic atoms interacting through a p-wave Feshbach resonance as, for example, realized in a {sup 85}Rb-{sup 87}Rb mixture. We show that, in addition to a conventional atomic and a p-wave molecular spinor-1 superfluidity at large positive and negative detunings, respectively, the system generically exhibits a finite-momentum atomic-molecular superfluidity at intermediate detuning around the unitary point. We analyze the detailed nature of the corresponding phases and the associated quantum and thermal phase transitions.

  8. New predictions for inclusive heavy-quarkonium P-wave decays.

    PubMed

    Brambilla, Nora; Eiras, Dolors; Pineda, Antonio; Soto, Joan; Vairo, Antonio

    2002-01-01

    We show that some nonrelativistic quantum chromodynamics color-octet matrix elements can be written in terms of (derivatives of) wave functions at the origin and of nonperturbative universal constants once the factorization between the soft and ultrasoft scales is achieved by using an effective field theory where only ultrasoft degrees of freedom are kept as dynamical entities. This allows us to derive a new set of relations between inclusive heavy-quarkonium P-wave decays into light hadrons with different principal quantum numbers and with different heavy flavors. In particular, we can estimate the ratios of the decay widths of bottomonium P-wave states from charmonium data. PMID:11800937

  9. Pairing symmetry and vortex zero mode for superconducting Dirac fermions

    SciTech Connect

    Lu, C.-K.; Herbut, Igor F.

    2010-10-01

    We study vortex zero-energy bound states in presence of pairing between low-energy Dirac fermions on the surface of a topological insulator. The pairing symmetries considered include the s-wave, p-wave, and, in particular, the mixed-parity symmetry, which arises in absence of the inversion symmetry on the surface. The zero mode is analyzed within the generalized Jackiw-Rossi-Dirac Hamiltonian that contains a momentum-dependent mass term, and includes the effects of the electromagnetic gauge field and the Zeeman coupling as well. At a finite chemical potential, as long as the spectrum without the vortex is fully gapped, the presence of a single Fermi surface with a definite helicity always leads to one Majorana zero mode, in which both electron's spin projections participate. In particular, the critical effects of the Zeeman coupling on the zero mode are discussed.

  10. Relationship of P-wave seismic attributes, azimuthal anisotropy, and commercial gas pay in 3-D P-wave multiazimuth data, Rulison field, Piceance Basin, Colorado

    SciTech Connect

    Lynn, H.B.; Campagna, D.; Simon, K.M.; Beckham, W.E.

    1999-08-01

    This case history is one of three field projects funded by the US Department of Energy a part of its ongoing research effort aimed to expand current levels of drilling and production efficiency in naturally-fractured tight-gas reservoirs. The original states goal for the 3-D P-wave seismic survey was to evaluate and map fracture azimuth and relative fracture density throughout a naturally-fractured gas reservoir interval. At Rulison field, this interval is the Cretaceous Mesaverde, approximately 2,500 ft (760 m) of lenticular sands, silts, and shales. Three-dimensional full-azimuth P-wave data were acquired for the evaluation of azimuthal anisotropy and the relationship of the anisotropy to commercial pay in the target interval. The methodology is based on the evaluation of two restricted-azimuth orthogonal (source receiver azimuth) 3-D P-wave volumes aligned with the natural principal axes of the azimuthal anisotropy, as estimated from velocity analysis of multiazimuth prestack gathers. The Dix interval velocity, as well as the interval amplitude variation with offset (AVO) gradient, was calculated for both azimuths for the gas-saturated Mesaverde interval. The two seismic attributes best correlated with commercial gas pay (at a 21-well control set) were (1) values greater than 4% azimuthal variation in the interval velocity ratio (source-receiver azimuth N60E/N30W) of the target interval (the gas-saturated Mesaverde), and (2) the sum of the interval AVO gradients (N60E + N30W). The sum of the interval AVO gradients is an attribute sensitive to the presence of gas, but not diagnostic of an azimuthal variation in the amplitude. The two-azimuth interval velocity anisotropy mapped over the survey area suggests spatial variations in the orientation of the maximum horizontal stress field and the open (to flow) fracture system.

  11. P wave velocity structure below India and Tibet incorporating anisotropic delay time effects

    NASA Astrophysics Data System (ADS)

    Mohanty, Debasis D.; Singh, Arun; O'Driscoll, Leland J.; Ravi Kumar, M.; Srinagesh, D.; Humphreys, Eugene D.

    2016-03-01

    We incorporate the effects of anisotropy to refine the continental-scale 3-D isotropic velocity model previously produced for India and Tibet by inverting 52,050 teleseismic P wave residuals. We have exploited a total of 1648 individual SKS splitting parameters to calculate the P wave travel time corrections due to azimuthal anisotropy. Our results suggest that anisotropy affects the P wave delays significantly (-0.3 to +0.5 s). Integration of these corrections into the 3-D modeling is achieved in two ways: (a) a priori adjustment to the delay time vector and (b) inverting only for anisotropic delays by introducing strong damping above 80 km and below 360 km depths and then subtracting the obtained anisotropic artifact image from the isotropic image, to get the corrected image. Under the assumption of azimuthal anisotropy resulting from lattice preferred orientation (LPO) alignment due to horizontal flow, the bias in isotropic P wave tomographic images is clear. The anisotropy corrected velocity perturbations are in the range of ±1.2% at depths of around 150 km and reduced further at deeper levels. Although the bias due to anisotropy does not affect the gross features, it does introduce certain artifacts at deeper levels.

  12. P-wave holographic superconductor/insulator phase transitions affected by dark matter sector

    NASA Astrophysics Data System (ADS)

    Rogatko, Marek; Wysokinski, Karol I.

    2016-03-01

    The holographic approach to building the p-wave superconductors results in three different models: the Maxwell-vector, the SU(2) Yang-Mills and the helical. In the probe limit approximation, we analytically examine the properties of the first two models in the theory with dark matter sector. It turns out that the effect of dark matter on the Maxwell-vector p-wave model is the same as on the s-wave superconductor studied earlier. For the non-Abelian model we study the phase transitions between p-wave holographic insulator/superconductor and metal/superconductor. Studies of marginally stable modes in the theory under consideration allow us to determine features of p-wave holographic droplet in a constant magnetic field. The dependence of the superconducting transition temperature on the coupling constant α to the dark matter sector is affected by the dark matter density ρD . For ρ D > ρ the transition temperature is a decreasing function of α. The critical chemical potential μ c for the quantum phase transition between insulator and metal depends on the chemical potential of dark matter μ D and for μ D = 0 is a decreasing function of α.

  13. Inversion of P-wave traveltimes from a VSP experiment in a homogeneous anisotropic medium

    NASA Astrophysics Data System (ADS)

    Ruzek, Bohuslav; Psencik, Ivan

    2016-04-01

    Determination of seismic anisotropy of rock environment plays an important role both in structural and exploration seismology. Knowledge of the orientation and strength of anisotropy has important geological implications as, e.g., estimation of the orientation of structural elements (layering, dikes, fissures) or of the orientation of the tectonic stress. The goal of this contribution is to test, first in a homogeneous model, the P-wave traveltime inversion based on weak-anisotropy approximation. In this approximation, traveltimes depend, approximately, on 15 P-wave weak-anisotropy (WA) parameters representing an alternative to the standard parameterization by a stiffness tensor. A typical VSP (vertical seismic profiling) configuration is considered, which guarantees relatively high angular illumination of a medium. As observed data, exact P-wave traveltimes generated in homogeneous orthorhombic media of arbitrary orientation, noise free or with added Gaussian noise are used. Results of the inversion are estimates of 15 P-wave WA parameters with corresponding resolution and covariance matrices. Properties of resolution matrices indicate quality of the measurement configuration. Properties of covariance matrices allow us to estimate the accuracy, with which individual WA parameters are determined. Results of a number of synthetic tests for varying source-receiver configurations, two velocity approximations, varying noise types/levels, etc. are presented.

  14. Laboratory velocities and attenuation of p-waves in limestones during freeze-thaw cycles

    SciTech Connect

    Remy, J.M.; Bellanger, M.; Homand-Etienne, F. )

    1994-02-01

    The velocity and the attenuation of compressional P-waves, measured in the laboratory at ultrasonic frequencies during a series of freezing and thawing cycles, are used as a method for predicting frost damage in a bedded limestone. Pulse transmission and spectral ratio techniques are used to determine the P-wave velocities and the attenuation values relative to an aluminum reference samples with very low attenuation. Limestone samples were water saturated under vacuum conditions, jacketed with rubber sleeves, and immersed in an antifreeze bath (50 percent methanol solution). They were submitted to repeated 24-hour freezing and thawing cycles simulating natural environment conditions. During the freeze/thaw cycles, P-wave velocities and quality factor Q diminished rapidly in thawed rock samples, indicating modification of the pore space. Measurements of crack porosity were conducted by hydrostatic compression tests on cubic rock samples that had been submitted to these freeze/thaw cycles. These measurements are used as an index of crack formation. The hydrostatic compression tests confirmed the phases of rock damage that were shown by changes in the value of Q. Furthermore, comparison between Q values and crack porosity demonstrate that the variations of P-wave attenuation are caused by the creation of new cracks and not by the enlargement of pre-existing cracks.

  15. Simultaneous Local and Teleseismic P-Wave Velocity Tomography in Western Mexico

    NASA Astrophysics Data System (ADS)

    Escudero, C. R.; Alarcon, E.; Ochoa, J.; Nuñez-Cornu, F. J.

    2015-12-01

    In western Mexico, the subduction of the Rivera and Cocos plates beneath the North America plate has deformed and fragmented the overriding plate, forming several structural rifts and crustal blocks. To improve the current tomographic images of the continental crust and uppermost mantle in this complex area, we used P-wave arrivals of local and teleseismic earthquakes along with the Fast Marching Method tomography technique. Our traveltime datasets include 2100 local earthquakes P-wave arrival times and 5,062 P-wave relative arrival time residuals of teleseismic earthquakes. The local earthquake phase picking was manually corrected and the relative arrival time residuals were estimated using the Multi-Channel Cross-Correlation method. All earthquakes occurred between 2006 and 2007 and were recorded by seismic stations deployed during the Mapping the Rivera Subduction Zone (MARS) experiment. The temporal seismic network consisted of 50 stations equipped with Streckeisen STS-2 and Quanterra Q330. We use an iterative nonlinear tomographic procedure and the fast marching method to map the residual patterns as P wave velocity anomalies. We followed an inversion scheme consisting of: (1) selection of a local and teleseismic earthquake, (2) estimation of improved 1-D reference velocity model, and (3) checkerboard testing to determine the optimum configuration of the velocity nodes, and inversion parameters, finally (4) perform final tomography and results analysis.

  16. Impact of hemodialysis on P-wave amplitude, duration, and dispersion.

    PubMed

    Drighil, Abdenasser; Madias, John E; El Mosalami, Hanane; El Badaoui, Nadia; Mouine, Bahija; Fadili, Wafae; Ramdani, Beenyouness; Bennis, Ahmed

    2007-01-01

    Atrial fibrillation (AF) is a frequent arrhythmia in patients undergoing hemodialysis (HD). P wave duration (PWdu) and P wave dispersion (PWdi) have been shown to be predictors of emerging AF in different clinical conditions. We sought to study the impact of HD on PWdu, PWdi, and P wave amplitude in a cohort of patients undergoing HD. Seventeen patients (8 men, 31+/-10 years) were studied. Echocardiography parameters, the sum of the amplitude of P waves in all 12 ECG leads (SP), mean PWdu, and PWdi, along with a host of other parameters (body weight, heart rate, electrolytes and hemoglobin/hematochrit) were measured 1/2h, before and after, HD. SP increased (11.8+/-3.9 vs 15.3+/-4.0 mm, p = 0.004), mean PWdu remained stable (82.7+/-11.1 vs 81.6+/-10.5 ms, p = 0.606), PWdi decreased (51.7+/-19.1 vs 41.7+/-19.1 ms, p = 0.03), and left atrial dimension decreased (37.96+/-3.90 vs 30.62+/-3.38 mm, p = 0.0001), after HD. The change in PWdi correlated with fluid removed by HD (r = -0.55, p = 0.022). Re-measurements of P-wave parameters in a random group of 11 of the 17 patients revealed augmented SP (p = 0.01), and stable mean PWdu (p = 0.36), and PWdi (p = 0.31), after HD. Fluid removed by HD leads to an increase in SP, a stable mean PWdu, and decrease (or stability on re-measurement in a subgroup of patients) in PWdi. Stability of PWdu may be due to the effects of augmentation of the P-wave amplitude and the reduction of the left atrial volume, cancelling each other. Variability of PWdi may stem from the occasional impossibility to measure PWdu (or measure it correctly) in minute P-waves in certain ECG leads, which in turn profoundly affects the PWdi. PMID:17538700

  17. Type 2 Diabetes Induces Prolonged P-wave Duration without Left Atrial Enlargement

    PubMed Central

    2016-01-01

    Prolonged P-wave duration has been observed in diabetes. However, the underlying mechanisms remain unclear. The aim of this study was to elucidate the possible mechanisms. A rat model of type 2 diabetes mellitus (T2DM) was used. P-wave durations were obtained using surface electrocardiography and sizes of the left atrium were determined using echocardiography. Cardiac inward rectifier K+ currents (Ik1), Na+ currents (INa), and action potentials were recorded from isolated left atrial myocytes using patch clamp techniques. Left atrial tissue specimens were analyzed for total connexin-40 (Cx40) and connexin-43 (Cx43) expression levels on western-blots. Specimens were also analyzed for Cx40 and Cx43 distribution and interstitial fibrosis by immunofluorescent and Masson trichrome staining, respectively. The mean P-wave duration was longer in T2DM rats than in controls; however, the mean left atrial sizes of each group of rats were similar. The densities of Ik1 and INa were unchanged in T2DM rats compared to controls. The action potential duration was longer in T2DM rats, but there was no significant difference in resting membrane potential or action potential amplitude compared to controls. The expression level of Cx40 protein was significantly lower, but Cx43 was unaltered in T2DM rats. However, immunofluorescent labeling of Cx43 showed a significantly enhanced lateralization. Staining showed interstitial fibrosis was greater in T2DM atrial tissue. Prolonged P-wave duration is not dependent on the left atrial size in rats with T2DM. Dysregulation of Cx40 and Cx43 protein expression, as well as fibrosis, might partly account for the prolongation of P-wave duration in T2DM. PMID:27051235

  18. Type 2 Diabetes Induces Prolonged P-wave Duration without Left Atrial Enlargement.

    PubMed

    Li, Bin; Pan, Yilong; Li, Xiaodong

    2016-04-01

    Prolonged P-wave duration has been observed in diabetes. However, the underlying mechanisms remain unclear. The aim of this study was to elucidate the possible mechanisms. A rat model of type 2 diabetes mellitus (T2DM) was used. P-wave durations were obtained using surface electrocardiography and sizes of the left atrium were determined using echocardiography. Cardiac inward rectifier K(+) currents (Ik1), Na(+) currents (INa), and action potentials were recorded from isolated left atrial myocytes using patch clamp techniques. Left atrial tissue specimens were analyzed for total connexin-40 (Cx40) and connexin-43 (Cx43) expression levels on western-blots. Specimens were also analyzed for Cx40 and Cx43 distribution and interstitial fibrosis by immunofluorescent and Masson trichrome staining, respectively. The mean P-wave duration was longer in T2DM rats than in controls; however, the mean left atrial sizes of each group of rats were similar. The densities of Ik1 and INa were unchanged in T2DM rats compared to controls. The action potential duration was longer in T2DM rats, but there was no significant difference in resting membrane potential or action potential amplitude compared to controls. The expression level of Cx40 protein was significantly lower, but Cx43 was unaltered in T2DM rats. However, immunofluorescent labeling of Cx43 showed a significantly enhanced lateralization. Staining showed interstitial fibrosis was greater in T2DM atrial tissue. Prolonged P-wave duration is not dependent on the left atrial size in rats with T2DM. Dysregulation of Cx40 and Cx43 protein expression, as well as fibrosis, might partly account for the prolongation of P-wave duration in T2DM. PMID:27051235

  19. Form analysis using digital signal processing reliably discriminates far-field R waves from P waves.

    PubMed

    Van Hemel, Norbert M; Wohlgemuth, Peter; Engbers, Jos G; Lawo, Thomas; Nebaznivy, Jan; Taborsky, Milos; Witte, Joachim; Boute, Wim; Munneke, Dave; Van Groeningen, Chris

    2004-12-01

    The correct detection of atrial arrhythmias by pacemakers is often limited by the presence of far-field R waves (FFRWs) in the atrial electrogram. Digital signal processing (DSP) of intracardiac signals is assumed to provide improved discrimination between P waves and FFRWs when compared to current methods. For this purpose, 100 bipolar and unipolar intracardiac atrial recordings from 31 patients were collected during pacemaker replacement and used for the off-line application of a novel DSP algorithm. Digital processing of the atrial intracardiac electrogram (IEGM) signals (8 bit, 800 samples/s) included filtering and calculation of the maximum amplitude and slope of the detected events. The form parameter was calculated, being the sum of the most negative value of the amplitude and that of the slope of the detected event. The algorithm collects form parameter data of P waves and FFRWs and composes histograms of these data. A sufficiently large gap between the FFRW and P wave histograms allows discrimination of these two signals based on form parameters. Three independent observers reviewed the reliability of classification with this algorithm. Sensitivity and specificity of FFRW detection were 99.63% and 100%, respectively, and no P waves were falsely classified. It can be concluded that this novel DSP algorithm shows excellent discrimination of FFRWs under off-line conditions and justify the implementation of this algorithm in future pacemakers for real-time discrimination between P waves and FFRWs. This method prevents false mode switching and allows correct and immediate intervention pacing for atrial tachyarrhythmias. PMID:15613124

  20. Anisotropic changes in P-wave velocity and attenuation during deformation and fluid infiltration of granite

    USGS Publications Warehouse

    Stanchits, S.A.; Lockner, D.A.; Ponomarev, A.V.

    2003-01-01

    Fluid infiltration and pore fluid pressure changes are known to have a significant effect on the occurrence of earthquakes. Yet, for most damaging earthquakes, with nucleation zones below a few kilometers depth, direct measurements of fluid pressure variations are not available. Instead, pore fluid pressures are inferred primarily from seismic-wave propagation characteristics such as Vp/Vs ratio, attenuation, and reflectivity contacts. We present laboratory measurements of changes in P-wave velocity and attenuation during the injection of water into a granite sample as it was loaded to failure. A cylindrical sample of Westerly granite was deformed at constant confining and pore pressures of 50 and 1 MPa, respectively. Axial load was increased in discrete steps by controlling axial displacement. Anisotropic P-wave velocity and attenuation fields were determined during the experiment using an array of 13 piezoelectric transducers. At the final loading steps (86% and 95% of peak stress), both spatial and temporal changes in P-wave velocity and peak-to-peak amplitudes of P and S waves were observed. P-wave velocity anisotropy reached a maximum of 26%. Transient increases in attenuation of up to 483 dB/m were also observed and were associated with diffusion of water into the sample. We show that velocity and attenuation of P waves are sensitive to the process of opening of microcracks and the subsequent resaturation of these cracks as water diffuses in from the surrounding region. Symmetry of the orientation of newly formed microcracks results in anisotropic velocity and attenuation fields that systematically evolve in response to changes in stress and influx of water. With proper scaling, these measurements provide constraints on the magnitude and duration of velocity and attenuation transients that can be expected to accompany the nucleation of earthquakes in the Earth's crust.

  1. Open fermionic quantum systems

    SciTech Connect

    Artacho, E.; Falicov, L.M. Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 )

    1993-01-15

    A method to treat a quantum system in interaction with a fermionic reservoir is presented. Its most important feature is that the dynamics of the exchange of particles between the system and the reservoir is explicitly included via an effective interaction term in the Hamiltonian. This feature gives rise to fluctuations in the total number of particles in the system. The system is to be considered in its full structure, whereas the reservoir is described only in an effective way, as a source of particles characterized by a small set of parameters. Possible applications include surfaces, molecular clusters, and defects in solids, in particular in highly correlated electronic materials. Four examples are presented: a tight-binding model for an adsorbate on the surface of a one-dimensional lattice, the Anderson model of a magnetic impurity in a metal, a two-orbital impurity with interorbital hybridization (intermediate-valence center), and a two-orbital impurity with interorbital repulsive interactions.

  2. Unlocking fermionic mode entanglement

    NASA Astrophysics Data System (ADS)

    Friis, Nicolai

    2016-06-01

    Aside from other puzzling features of entanglement, it has been debated whether a physically meaningful notion of entanglement requires two (or more) particles as carriers of the correlated degrees-of-freedom, or if a single particle could be considered to be entangled as well. While the usefulness of single-boson entanglement has been demonstrated some time ago, the restrictions of superselection rules have previously thwarted attempts at similar arguments for single fermions. In Dasenbrook et al (2016 New J. Phys. 18 043036) this obstacle is overcome. The authors propose a scheme for a Bell test on two copies of single-electron states whose entanglement is individually not accessible. The discussed scheme, which makes use of recent progress in electronic quantum optics, provides an experimentally viable and theoretically unambiguous way to assert that certain single-electron states can be considered to be entangled.

  3. Dynamical symmetries for fermions

    SciTech Connect

    Guidry, M.

    1989-01-01

    An introduction is given to the Fermion Dynamical Symmetry Model (FDSM). The analytical symmetry limits of the model are then applied to the calculation of physical quantities such as ground-state masses and B(E{sub 2}) values in heavy nuclei. These comparisons with data provide strong support for a new principle of collective motion, the Dynamical Pauli Effect, and suggest that dynamical symmetries which properly account for the pauli principle are much more persistent in nuclear structure than the corresponding boson symmetries. Finally, we present an assessment of criticisms which have been voiced concerning the FDSM, and a discussion of new phenomena and exotic spectroscopy'' which may be suggested by the model. 14 refs., 8 figs., 4 tabs.

  4. Center-of-Mass Baton.

    ERIC Educational Resources Information Center

    Bucher, Manfred; And Others

    1991-01-01

    Described is a baton that consists of an unbreakable transparent tube with three inserted light-emitting diodes (LED) and terminal impact buffers that hold batteries and counterweights. The concepts of projectile motion and parabolic paths can be shown by analyzing the path of a thrown baton. (KR)

  5. FLIC Fermions and Hadron Phenomenology

    SciTech Connect

    D. Leinweber; J.N. Hedditch; W. Melnitchouk; A.W. Thomas; A.G. Williams; R.D. Young; J.M. Zanotti; J.B. Zhang

    2002-06-01

    A pedagogical overview of the formulation of the Fat Link Irrelevant Clover (FLIC) fermion action and its associated phenomenology is described. The scaling analysis indicates FLIC fermions provide a new form of nonperturbative order (a) improvement where near-continuum results are obtained at finite lattice spacing. Spin-1/2 and spin-3/2, even and odd parity baryon resonances are investigated in quenched QCD, where the nature of the Roper resonance and Lambda (1405) are of particular interest. FLIC fermions allow efficient access to the light quark-mass regime, where evidence of chiral nonanalytic behavior in the Delta mass is observed.

  6. The dijet cross section measurement in proton-proton collisions at a center of mass energy of 500 GeV at STAR

    NASA Astrophysics Data System (ADS)

    Webb, Grant

    Polarized deep inelastic scattering experiments play a vital role in the exploration of the spin structure of the proton. The polarized proton-proton collider at RHIC provides direct access to the gluon spin distribution through longitudinal double spin asymmetry measurements of inclusive jets, pions, and dijets. This thesis presents the measurement of the dijet double differential cross-section in proton-proton collisions at center of mass energies of [sq rt]s = 500 GeV. The data represent an integrated luminosity of 8.7 pb--1 recorded by the STAR detector during the 2009 RHIC run. A comprehensive jet analysis was performed to determine the ideal jet algorithm and jet parameters used in [sq rt]s = 500 GeV collisions at the STAR detector. The cross-section is measured as a function of the dijet invariant mass (30 ≤ Mij ≤ 152 GeV) in the mid rapidity region with a maximum rapidity range of | ymax| ≤ 0.8. This result shows agreement with theoretical next-to-leading order pQCD calculations, motivating the use of dijet asymmetries at STAR to further constrain the shape of Deltag( x). KEYWORDS: Dijet Cross Section, Gluon Spin, STAR Detector, Jetography, Embedding.

  7. Inclusive hadron production and two particle correlations in e/sup +/e/sup -/ annihilation at 29 GeV center-of-mass energy

    SciTech Connect

    Shapiro, M.

    1984-12-01

    We have studied hadron production in e/sup +/e/sup -/ annihilation at 29 GeV center-of-mass energy using the PEP-4 Time Projection Chamber Detector. The inclusive cross sections and mean multiplicities for ..pi../sup + -/, K/sup + -/ and (p + anti p) production have been measured using ionization energy loss to separate particle species. We find on average 10.7 +- 0.6 ..pi../sup + -/, 1.35 +- .13 K/sup + -/ and 0.60 +- 0.08 (p + anti p) per multihadron event. The differential cross section is well described by a number of Monte Carlo hadronization models. In addition, we have observed correlations in rapidity space for identified pions and kaons. Short-range KK correlations provide evidence for local flavor compensation during hadronization. Long-range ..pi pi.. and KK correlations indicate that the initial partons carry flavor. We also observe significant long-range ..pi..K correlations as a result of heavy quark decays. 85 references, 67 figures, 11 tables.

  8. Bose-Einstein correlations of pions in e/sup +/e/sup minus/ annihilation at 29 GeV center-of-mass energy

    SciTech Connect

    Avery, R.E.

    1989-01-13

    Measurements of two- and three-particle correlations between like-sign pions produced in e/sup +/e/sup minus/ annihilation at 29 GeV center-of-mass energy are presented. The analysis is based on data taken during the period 1982--1986 using the TPC/2..gamma.. detector at PEP. Two-particle correlations are studied as a function of Q, the momentum difference as measured in the rest frame of the pion pair, and as a function of q/sub 0/, the energy difference as measured in the lab frame. The Bose-Einstein enhancement is observed when Q is small even when the energy difference, q/sub 0/, is substantial. This observation provides evidence that the Bose-Einstein correlations are best described by a model that correctly accounts for the relativistic motion of the particle sources. Three-pion correlations are measured both by using a standard three-pion correlation function, and also by using a correlation function for which the correlations between the pairs of pions within the triplet have been subtracted. The observation of three-pion correlations after pair correlations have been subtracted supports the interpretation that the observed correlations are due to Bose-Einstein interference. 56 refs.

  9. A combined model for pseudorapidity distributions in p-p collisions at center-of-mass energies from 23.6 to 7000 GeV

    NASA Astrophysics Data System (ADS)

    Jiang, Zhi-Jin; Huang, Yan; Wang, Jie

    2016-07-01

    In p-p collisions, the charged particles produced consist of two leading particles and those frozen out from the hot and dense matter created in the collisions. The two leading particles are in the projectile and target fragmentation regions, respectively, which, in this paper, are conventionally supposed to have Gaussian rapidity distributions. The hot and dense matter is assumed to expand according to unified hydrodynamics, a hydrodynamic model which unifies the features of the Landau and Hwa-Bjorken models, and freeze out into charged particles from a space-like hypersurface with a fixed proper time of τ FO. The rapidity distribution of these charged particles can be derived analytically. The combined contribution from both leading particles and unified hydrodynamics is then compared against experimental data from a now available center-of-mass energy region from 23.6 to 7000 GeV. The model predictions are consistent with experimental measurements. Supported by Hujiang Foundation of China (B14004) and Shanghai Key Lab of Modern Optical System

  10. On Saturn's rotation relative to a center of mass under the action of the gravitational moments of the Sun and Jupiter

    NASA Astrophysics Data System (ADS)

    Krasilnikov, P. S.; Amelin, R. N.

    2016-03-01

    Saturn's rotation relative to a center of mass is considered within an elliptic restricted three-body problem. It is assumed that Saturn is a solid under the action of gravity of the Sun and Jupiter. The motions of Saturn and Jupiter are considered elliptic with small eccentricities e S and e J , respectively; the mean motion of Jupiter n J is also small. We obtain the averaged Hamiltonian function for a small parameter of ɛ = n J and integrals of evolution equations. The main effects of the influence of Jupiter on Saturn's rotation are described: (α) the evolution of the constant parameters of regular precession for the angular momentum vector I2; (β) the occurrence of new libration zones of oscillations I2 near the plane of the celestial equator parallel to the plane of the Jupiter's orbit; (γ) the occurrence of additional unstable equilibria of vector I2 at the points of the north and south poles of the celestial sphere and, as a result, the existence of homoclinic trajectories; and (δ) the existence of periodic trajectories with arbitrarily large periods near the homoclinic trajectory. It is shown that the effects of (β), (γ), and (δ) are caused by the eccentricity e of the Jupiter's orbit and are practically independent of Jupiter's mass (within satellite approximation).

  11. Centrality and Pseudorapidity Dependence of the Transverse Energy Flow in pPb collisions at Center of Mass Energy 5.02 TeV

    NASA Astrophysics Data System (ADS)

    Bruner, Christopher Ryan Edwards

    The almost hermitic coverage of CMS is used to measure the distribution of transverse energy as a function of pseudorapidity for pPb collisions at center of mass energy of 5:02 TeV. For minimum bias collisions (1/N) dET/deta reaches 25 GeV which implies an energy density comparable to that of PbPb collisions at TeV energies. The centrality dependence of transverse energy dependence has been studied using centrality measures defined in three different angular regions. The correlations between which events are selected by are much wider than they were in PbPb collisions and are not reproduced by either the EPOS-LHC or HIJING event generators. Each centrality class was divided by the most central events in order to measure the auto-correlations induced by a centrality definition and reduce the systematic error. This variable is called SPC and the effect of the auto-correlation persists over a much wider pseudo-rapidity range than predicted by either of the event generators.

  12. Measurements of the charged underlying event with the ATLAS detector at 7TeV & 900 GeV center of mass energies

    NASA Astrophysics Data System (ADS)

    Hare, Gabriel Archacki

    Proton collisions simultaneously access very high energies through parton scattering and low energy effects through parton correlations. While the interactions of partons at high energies are well described by perturbative parton calculations, simulations of low energy interactions of the quark and gluon partons are based on models rather than well-defined approximations from first principles. In proton collisions that are selected for high energy physics studies one pair of partons carries a large fraction of the energy of the colliding protons. In addition to this primary parton scattering it is expected that there will be secondary interactions of additional parton pairs yielding an "Underlying Event." Measuring correlations between the primary and secondary scattering provides some insight into the modeling of low-energy QCD. The first measurements of the Underlying Event by the ATLAS detector at 900 GeV and 7 TeV center of mass energies are presented. For these measurements the highest transverse momentum reconstructed track is used to characterize the energy and orientation of the primary scattering of partons. The results of these measurements indicate a higher mean multiplicity of particles arising from secondary interactions than was predicted by models tuned to measurements made at lower energies. In the context of a Negative Binomial distribution for particle multiplicities these results indicate that the measured Negative Binomial distribution is more Exponential than was predicted by any contemporaneous model of hadron production.

  13. Search for Scalar Bottom Quarks from Gluino Decays in Proton - Anti-proton Collisions at a Center-of-Mass Energy of 1.96-TeV

    SciTech Connect

    Rott, Carsten

    2004-12-01

    The authors have performed a search for the scalar bottom quark ({tilde b}{sub 1}) from gluino ({tilde g}) decays in an R-parity conserving SUSY scenario with m{sub {tilde g}} > m{sub {tilde b}{sub 1}}, by investigating a final state of large missing transverse energy, with three or more jets, and some of them from the hadronization of b-quarks. A data sample of 156 pb{sup -1} collected by the Collider Detector at Fermilab at a center-of-mass energy of {radical}s = 1.96 TeV was used. For the final selection, jets containing secondary displaced vertices were required. This analysis has been performed ''blind'', in that the inspection of the signal region was only made after the Standard Model prediction was finalized. Comparing data with SUSY predictions, they can exclude masses of the gluino and sbottom of up to 280 and 240 GeV/c{sup 2} respectively.

  14. A calorimetric measurement of the strong coupling constant in electron-positron annihilation at a center-of-mass energy of 91.6 GeV

    SciTech Connect

    Martirena, S.G.

    1994-04-01

    In this work, a measurement of the strong coupling constant {alpha}{sub s} in e{sup +}e{sup {minus}} annihilation at a center-of-mass energy of 91.6 GeV is presented. The measurement was performed with the SLD at the Stanford Linear Collider facility located at the Stanford Linear Accelerator Center in California. The procedure used consisted of measuring the rate of hard gluon radiation from the primary quarks in a sample of 9,878 hadronic events. After defining the asymptotic manifestation of partons as `jets`, various phenomenological models were used to correct for the hadronization process. A value for the QCD scale parameter {Lambda}{sub bar MS}, defined in the {sub bar MS} renormalization convention with 5 active quark flavors, was then obtained by a direct fit to O({alpha}{sub s}{sup 2}) calculations. The value of {alpha}{sub s} obtained was {alpha}{sub s}(M{sub z0}) = 0.122 {plus_minus} 0.004 {sub {minus}0.007} {sup +0.008} where the uncertainties are experimental (combined statistical and systematic) and theoretical (systematic) respectively. Equivalently, {Lambda}{sub bar MS} = 0.28 {sub {minus}0.10}{sup +0.16} GeV where the experimental and theoretical uncertainties have been combined.

  15. Similar muscles contribute to horizontal and vertical acceleration of center of mass in forward and backward walking: implications for neural control.

    PubMed

    Jansen, Karen; De Groote, Friedl; Massaad, Firas; Meyns, Pieter; Duysens, Jacques; Jonkers, Ilse

    2012-06-01

    Leg kinematics during backward walking (BW) are very similar to the time-reversed kinematics during forward walking (FW). This suggests that the underlying muscle activation pattern could originate from a simple time reversal, as well. Experimental electromyography studies have confirmed that this is the case for some muscles. Furthermore, it has been hypothesized that muscles showing a time reversal should also exhibit a reversal in function [from accelerating the body center of mass (COM) to decelerating]. However, this has not yet been verified in simulation studies. In the present study, forward simulations were used to study the effects of muscles on the acceleration of COM in FW and BW. We found that a reversal in function was indeed present in the muscle control of the horizontal movement of COM (e.g., tibialis anterior and gastrocnemius). In contrast, muscles' antigravity contributions maintained their function for both directions of movement. An important outcome of the present study is therefore that similar muscles can be used to achieve opposite functional demands at the level of control of the COM when walking direction is reversed. However, some muscles showed direction-specific contributions (i.e., dorsiflexors). We concluded that the changes in muscle contributions imply that a simple time reversal would be insufficient to produce BW from FW. We therefore propose that BW utilizes extra elements, presumably supraspinal, in addition to a common spinal drive. These additions are needed for propulsion and require a partial reconfiguration of lower level common networks. PMID:22423005

  16. Observation and studies of jet quenching in PbPb collisions at nucleon-nucleon center-of-mass energy = 2.76 TeV

    SciTech Connect

    Chatrchyan, Serguei; et al.

    2011-08-01

    Jet production in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV was studied with the CMS detector at the LHC, using a data sample corresponding to an integrated luminosity of 6.7 inverse microbarns. Jets are reconstructed using the energy deposited in the CMS calorimeters and studied as a function of collision centrality. With increasing collision centrality, a striking imbalance in dijet transverse momentum is observed, consistent with jet quenching. The observed effect extends from the lower cut-off used in this study (jet transverse momentum = 120 GeV/c) up to the statistical limit of the available data sample (jet transverse momentum approximately 210 GeV/c). Correlations of charged particle tracks with jets indicate that the momentum imbalance is accompanied by a softening of the fragmentation pattern of the second most energetic, away-side jet. The dijet momentum balance is recovered when integrating low transverse momentum particles distributed over a wide angular range relative to the direction of the away-side jet.

  17. Observation of e⁺e⁻→ηJ/ψ at center-of-mass energy √s=4.009 GeV

    SciTech Connect

    Ablikim, M.; Achasov, M. N.; Ambrose, D. J.; An, F. F.; An, Q.; An, Z. H.; Bai, J. Z.; Ban, Y.; Becker, J.; Bennett, J. V.; Bertani, M.; Bian, J. M.; Boger, E.; Bondarenko, O.; Boyko, I.; Briere, R. A.; Bytev, V.; Cai, X.; Cakir, O.; Calcaterra, A.; Cao, G. F.; Cetin, S. A.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, Y. B.; Cheng, H. P.; Chu, Y. P.; Cronin-Hennessy, D.; Dai, H. L.; Dai, J. P.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; Ding, W. M.; Ding, Y.; Dong, L. Y.; Dong, M. Y.; Du, S. X.; Fang, J.; Fang, S. S.; Fava, L.; Feldbauer, F.; Feng, C. Q.; Ferroli, R. B.; Fu, C. D.; Fu, J. L.; Gao, Y.; Geng, C.; Goetzen, K.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, Y. P.; Han, Y. L.; Harris, F. A.; He, K. L.; He, M.; He, Z. Y.; Held, T.; Heng, Y. K.; Hou, Z. L.; Hu, H. M.; Hu, J. F.; Hu, T.; Huang, G. M.; Huang, J. S.; Huang, X. T.; Huang, Y. P.; Hussain, T.; Ji, C. S.; Ji, Q.; Ji, X. B.; Ji, X. L.; Jiang, L. L.; Jiang, X. S.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Jing, F. F.; Kalantar-Nayestanaki, N.; Kavatsyuk, M.; Kuehn, W.; Lai, W.; Lange, J. S.; Li, C. H.; Li, Cheng; Li, Cui; Li, D. M.; Li, F.; Li, G.; Li, H. B.; Li, J. C.; Li, K.; Li, Lei; Li, Q. J.; Li, S. L.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, X. R.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Liao, X. T.; Liu, B. J.; Liu, C. L.; Liu, C. X.; Liu, C. Y.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H.; Liu, H. B.; Liu, H. H.; Liu, H. M.; Liu, H. W.; Liu, J. P.; Liu, K. Y.; Liu, Kai; Liu, P. L.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, X. H.; Liu, Y. B.; Liu, Z. A.; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H.; Lu, G. R.; Lu, H. J.; Lu, J. G.; Lu, Q. W.; Lu, X. R.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lv, M.; Ma, C. L.; Ma, F. C.; Ma, H. L.; Ma, Q. M.; Ma, S.; Ma, T.; Ma, X. Y.; Ma, Y.; Maas, F. E.; Maggiora, M.; Malik, Q. A.; Mao, Y. J.; Mao, Z. P.; Messchendorp, J. G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Morales, C. Morales; Motzko, C.; Muchnoi, N. Yu.; Muramatsu, H.; Nefedov, Y.; Nicholson, C.; Nikolaev, I. B.; Ning, Z.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Park, J. W.; Pelizaeus, M.; Peng, H. P.; Peters, K.; Ping, J. L.; Ping, R. G.; Poling, R.; Prencipe, E.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, X. S.; Qin, Y.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Rong, G.; Ruan, X. D.; Sarantsev, A.; Schaefer, B. D.; Schulze, J.; Shao, M.; Shen, C. P.; Shen, X. Y.; Sheng, H. Y.; Shepherd, M. R.; Song, W. M.; Song, X. Y.; Spataro, S.; Spruck, B.; Sun, D. H.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Tapan, I.; Thorndike, E. H.; Toth, D.; Ullrich, M.; Varner, G. S.; Wang, B.; Wang, B. Q.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, Q.; Wang, Q. J.; Wang, S. G.; Wang, X. L.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. Y.; Wei, D. H.; Weidenkaff, P.; Wen, Q. G.; Wen, S. P.; Werner, M.; Wiedner, U.; Wu, L. H.; Wu, N.; Wu, S. X.; Wu, W.; Wu, Z.; Xia, L. G.; Xiao, Z. J.; Xie, Y. G.; Xiu, Q. L.; Xu, G. F.; Xu, G. M.; Xu, H.; Xu, Q. J.; Xu, X. P.; Xu, Z. R.; Xue, F.; Xue, Z.; Yan, L.; Yan, W. B.; Yan, Y. H.; Yang, H. X.; Yang, Y.; Yang, Y. X.; Ye, H.; Ye, M.; Ye, M. H.; Yu, B. X.; Yu, C. X.; Yu, J. S.; Yu, S. P.; Yuan, C. Z.; Yuan, Y.; Zafar, A. A.; Zallo, A.; Zeng, Y.; Zhang, B. X.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, S. H.; Zhang, X. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. H.; Zhang, Y. S.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, H. S.; Zhao, J. W.; Zhao, K. X.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, S. J.; Zhao, T. C.; Zhao, X. H.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, Y. H.; Zhong, B.; Zhong, J.; Zhou, L.; Zhou, X. K.; Zhou, X. R.; Zhu, C.; Zhu, K.; Zhu, K. J.; Zhu, S. H.; Zhu, X. L.; Zhu, X. W.; Zhu, Y. C.; Zhu, Y. M.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zou, B. S.; Zou, J. H.

    2012-10-01

    Using a 478 pb⁻¹ data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider storage ring at a center-of-mass energy of s√=4.009 GeV, the production of e⁺e⁻→ηJ/ψ is observed for the first time with a statistical significance of greater than 10σ. The Born cross section is measured to be (32.1±2.8±1.3) pb, where the first error is statistical and the second systematic. Assuming the ηJ/ψ signal is from a hadronic transition of the ψ(4040), the fractional transition rate is determined to be B(ψ(4040)→ηJ/ψ)=(5.2±0.5±0.2±0.5)×10⁻³, where the first, second, and third errors are statistical, systematic, and the uncertainty from the ψ(4040) resonant parameters, respectively. The production of e⁺e⁻→π0J/ψ is searched for, but no significant signal is observed, and B(ψ(4040)→π⁰J/ψ)<2.8×10⁻⁴ is obtained at the 90% confidence level.

  18. Observation of e⁺e⁻→ηJ/ψ at center-of-mass energy √s=4.009 GeV

    DOE PAGESBeta

    Ablikim, M.; Achasov, M. N.; Ambrose, D. J.; An, F. F.; An, Q.; An, Z. H.; Bai, J. Z.; Ban, Y.; Becker, J.; Bennett, J. V.; et al

    2012-10-01

    Using a 478 pb⁻¹ data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider storage ring at a center-of-mass energy of s√=4.009 GeV, the production of e⁺e⁻→ηJ/ψ is observed for the first time with a statistical significance of greater than 10σ. The Born cross section is measured to be (32.1±2.8±1.3) pb, where the first error is statistical and the second systematic. Assuming the ηJ/ψ signal is from a hadronic transition of the ψ(4040), the fractional transition rate is determined to be B(ψ(4040)→ηJ/ψ)=(5.2±0.5±0.2±0.5)×10⁻³, where the first, second, and third errors are statistical, systematic, and the uncertainty frommore » the ψ(4040) resonant parameters, respectively. The production of e⁺e⁻→π0J/ψ is searched for, but no significant signal is observed, and B(ψ(4040)→π⁰J/ψ)<2.8×10⁻⁴ is obtained at the 90% confidence level.« less

  19. Search for New Physics in a Final State with Same-Sign Dileptons, Jets, and Missing Transverse Energy at 7 TeV Center of Mass Energy

    SciTech Connect

    Golf, Frank, III

    2012-01-01

    We report on a search for new physics in a final state with two same sign leptons, missing transverse energy, and significant hadronic activity at a center of mass energy $\\sqrt{s}$ = 7 TeV. The data were collected with the CMS detector at the CERN LHC and correspond to an integrated luminosity of 0.98 $\\mathrm{fb}^{-1}$. Data--driven methods are developed to estimate the dominant Standard Model backgrounds. No evidence for new physics is observed. The dominant background to the analysis comes from failures of lepton identification in Standard Model $t\\bar{t}$ events. The $t\\bar{t}$ production cross section in the dilepton final state is measured using 3.1 $\\mathrm{fb}^{-1}$ of data. The cross section is measured to be 194 $\\pm$ 72 (stat) $\\pm$ 24 (syst) $\\pm$ 21 (lumi) pb. An algorithm is developed that uses tracking information to improve the reconstruction of missing transverse energy. The reconstruction of missing transverse energy is commissioned using the first collisio ns recorded at 0.9, 2.36 and 7 TeV data. Events with abnormally large values of missing transverse energy are identified as arising from anomalous signals in the calorimeters. Tools are developed to identify and remove these anomalous signals.

  20. Properties of jets measured from tracks in proton-proton collisions at center-of-mass energy root s=7 TeV with the ATLAS detector

    SciTech Connect

    Aad, G.; Abbott, B; Abdallah, J; Abdelalim, AA; Abdesselam, A; Abdinov, O; Abi, B; Abolins, M; Abramowicz, H; Abreu, H; Acerbi, E; Acharya, BS; Adams, DL; Addy, TN; Adelman, J; Aderholz, M; Adomeit, S; Adragna, P; Adye, T; Aefsky, S; Aguilar-Saavedra, JA

    2011-09-20

    Jets are identified and their properties studied in center-of-mass energy {radical}s = 7 TeV proton-proton collisions at the Large Hadron Collider using charged particles measured by the ATLAS inner detector. Events are selected using a minimum bias trigger, allowing jets at very low transverse momentum to be observed and their characteristics in the transition to high-momentum fully perturbative jets to be studied. Jets are reconstructed using the anti-k{sub t} algorithm applied to charged particles with two radius parameter choices, 0.4 and 0.6. An inclusive charged jet transverse momentum cross section measurement from 4 GeV to 100 GeV is shown for four ranges in rapidity extending to 1.9 and corrected to charged particle-level truth jets. The transverse momenta and longitudinal momentum fractions of charged particles within jets are measured, along with the charged particle multiplicity and the particle density as a function of radial distance from the jet axis. Comparison of the data with the theoretical models implemented in existing tunings of Monte Carlo event generators indicates reasonable overall agreement between data and Monte Carlo. These comparisons are sensitive to Monte Carlo parton showering, hadronization, and soft physics models.

  1. Properties of jets measured from tracks in proton-proton collisions at center-of-mass energy √s=7 TeV with the ATLAS detector

    DOE PAGESBeta

    Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; et al

    2011-09-20

    Jets are identified and their properties studied in center-of-mass energy √s=7 TeV proton-proton collisions at the Large Hadron Collider using charged particles measured by the ATLAS inner detector. Events are selected using a minimum bias trigger, allowing jets at very low transverse momentum to be observed and their characteristics in the transition to high-momentum fully perturbative jets to be studied. Jets are reconstructed using the anti-kt algorithm applied to charged particles with two radius parameter choices, 0.4 and 0.6. An inclusive charged jet transverse momentum cross section measurement from 4 GeV to 100 GeV is shown for four ranges inmore » rapidity extending to 1.9 and corrected to charged particle-level truth jets. The transverse momenta and longitudinal momentum fractions of charged particles within jets are measured, along with the charged particle multiplicity and the particle density as a function of radial distance from the jet axis. Comparison of the data with the theoretical models implemented in existing tunings of Monte Carlo event generators indicates reasonable overall agreement between data and Monte Carlo. These comparisons are sensitive to Monte Carlo parton showering, hadronization, and soft physics models.« less

  2. Search for Supersymmetry Using Diphoton Events in p anti-p Collisions at a center of mass energy of 1.96-TeV

    SciTech Connect

    Lee, Eun Sin

    2010-05-01

    This dissertation presents the results of a search for supersymmetry in protonantiproton collisions with a center of mass energy of 1.96 TeV studied with the Collider Detector at Fermilab. Our strategy is to select collisions with two photons in the nal state that have the properties of being the decays of very massive supersymmetric particles. This includes looking for large total energy from the decayed particles as well as for the presence of particles that leave the detector without interacting. We nd no events using 2.6 fb-1 of data collected during the 2004-2008 collider run of the Fermilab Tevatron which is consistent with the background estimate of 1.4 0.4 events. Since there is no evidence of new particles we set cross section limits in a gaugemediated supersymmetry model with X$\\tilde{o}$1→ eG, where the X$\\tilde{o}$1 and eG are the lightest neutralino and the gravitino (the lightest supersymmetric particle), respectively. We set limits on models as a function of the X$\\tilde{o}$1 mass and lifetime, producing the world's most sensitive search for X$\\tilde{o}$1 by excluding masses up to 149 GeV=c2 for X$\\tilde{o}$1 lifetimes much less than 1 ns.

  3. Topological Septet Pairing with Spin-3/2 Fermions: High-Partial-Wave Channel Counterpart of the 3He -B Phase

    NASA Astrophysics Data System (ADS)

    Yang, Wang; Li, Yi; Wu, Congjun

    2016-08-01

    We systematically generalize the exotic 3He -B phase, which not only exhibits unconventional symmetry but is also isotropic and topologically nontrivial, to arbitrary partial-wave channels with multicomponent fermions. The concrete example with four-component fermions is illustrated including the isotropic f -, p -, and d -wave pairings in the spin septet, triplet, and quintet channels, respectively. The odd partial-wave channel pairings are topologically nontrivial, while pairings in even partial-wave channels are topologically trivial. The topological index reaches the largest value of N2 in the p -wave channel (N is half of the fermion component number). The surface spectra exhibit multiple linear and even high order Dirac cones. Applications to multiorbital condensed matter systems and multicomponent ultracold large spin fermion systems are discussed.

  4. Topological Septet Pairing with Spin-3/2 Fermions: High-Partial-Wave Channel Counterpart of the ^{3}He-B Phase.

    PubMed

    Yang, Wang; Li, Yi; Wu, Congjun

    2016-08-12

    We systematically generalize the exotic ^{3}He-B phase, which not only exhibits unconventional symmetry but is also isotropic and topologically nontrivial, to arbitrary partial-wave channels with multicomponent fermions. The concrete example with four-component fermions is illustrated including the isotropic f-, p-, and d-wave pairings in the spin septet, triplet, and quintet channels, respectively. The odd partial-wave channel pairings are topologically nontrivial, while pairings in even partial-wave channels are topologically trivial. The topological index reaches the largest value of N^{2} in the p-wave channel (N is half of the fermion component number). The surface spectra exhibit multiple linear and even high order Dirac cones. Applications to multiorbital condensed matter systems and multicomponent ultracold large spin fermion systems are discussed. PMID:27563972

  5. P wave detection thresholds, Pn velocity estimates, and T wave location uncertainty from oceanic hydrophones

    NASA Astrophysics Data System (ADS)

    Slack, Philip D.; Fox, Christopher G.; Dziak, Robert P.

    1999-06-01

    P wave arrivals recorded by the U.S. Navy's SOund SUrveillance System (SOSUS) hydrophone arrays were used to estimate earthquake detection thresholds and Pn velocities in the northeast Pacific Ocean. The Navy hydrophones have been used successfully to detect and locate oceanic earthquakes using their waterborne acoustic tertiary (T) waves; however, use of these hydrophones for seismic body wave detection allows regional seismic analyses to be extended to the oceanic environment. The P wave detection threshold of the SOSUS hydrophones was quantified using the epicentral distance and magnitude of 250 northeast Pacific Ocean earthquakes. Earthquakes with body wave magnitudes as low as 2 have detectable P wave arrivals at epicentral distances of ≤500 km. Earthquakes with mb between 3.5 and 5 were detected ˜50% of the time at distances of 100-1500 km, while events with mb > 5 were all detected, even out to distances of 1000-1500 km. Both P and T wave hydrophone arrival times were used to estimate the epicenters of 100 earthquakes. The peak amplitude of the T wave coda and the onset of the P wave were used as the earthquake arrival times to estimate event locations. T wave arrival time residuals have a Gaussian distribution with zero mean, which implies that using T wave peak amplitude is consistent with using the P wave onset as the arrival time. There are typically ≤6 stations used to derive a T wave based location, hence location error ellipses are not well constrained. A Monte Carlo technique was employed to estimate T wave event location uncertainty. T wave locations have error bars of ˜1 km in latitude and longitude when >3 hydrophones are used for a location estimate. The detected P wave arrivals and earthquake locations were used to measure Pn velocities. Pn velocity values of 7.9 ± 0.1 and 8.0 ± 0.1 km/s were found for the Pacific and Juan de Fuca plates, respectively. A Pn velocity of 7.5 ± 0.1 km/s was measured for rays traveling northward from the

  6. P-wave and S-wave Tomography for Characterizing an Impoundment Dam

    NASA Astrophysics Data System (ADS)

    Link, C. A.; Betterly, S. J.; Romero, S.

    2005-05-01

    A data set consisting of vertical and shear component seismic data was recorded on the crest of an impoundment dam. The data were recorded for the purpose of characterizing the integrity of the dam before transferal of the property to the public domain. Cone penetrometer results were also available for comparison. Four sets of 24 channels were used to record data from 3-component spiked geophones and vertical component data from gimbaled geophones in a parallel land streamer configuration. A sledge hammer with flat plate and spiked shear source was used for vertical, transverse, and inline source orientations. Left-right and front-back hits were used to generate the shear data. At each source location, five orientations of the source were used: vertical, transverse left-right, inline front-back. Thus the final data set consists of nine-component data. A spread consisted of 24 one meter spaced receiver locations. The source was moved through the stationary spread starting and ending two meters off the spread ends for 28 shots per spread. A total of three spreads were shot with spread move-up of one-half spread length. Data processing was done using a diving wave tomography approach and Rayfract software. The tomography approach uses first arrivals. First arrivals for the shear data were picked from differenced transverse shot gathers to remove compressional wave contamination. The transverse shear gathers were equalized before differencing. The resulting P-wave and S-wave velocity profiles were subsequently used to calculate a Poisson's ratio profile for the dam. The P-wave velocity profile shows zones of high velocity, approximately that of water, correlating with suspected zones of seepage. These zones occur at a depth of nine meters. Near the top of the P-wave profile, two low velocity anomalies and one higher velocity anomaly are apparent. No independent data exist to confirm the nature of these anomalies. The S-wave velocity profile does not exhibit the

  7. Observing remnants by fermions' tunneling

    SciTech Connect

    Chen, D.Y.; Wu, H.W.; Yang, H. E-mail: iverwu@uestc.edu.cn

    2014-03-01

    The standard Hawking formula predicts the complete evaporation of black holes. In this paper, we introduce effects of quantum gravity into fermions' tunneling from Reissner-Nordstrom and Kerr black holes. The quantum gravity effects slow down the increase of Hawking temperatures. This property naturally leads to a residue mass in black hole evaporation. The corrected temperatures are affected by the quantum numbers of emitted fermions. Meanwhile, the temperature of the Kerr black hole is a function of θ due to the rotation.

  8. The influence of rock anisotropy on elliptical-polarization state of inhomogenously refracted P-wave

    NASA Astrophysics Data System (ADS)

    Fa, Lin; Zhao, Jie; Han, YongLan; Li, GuoHui; Ding, PengFei; Zhao, MeiShan

    2016-04-01

    This paper discusses the influence of the anisotropy parameters on elliptical-polarization of the inhomogenously refracted P-wave induced at VTI-media interface. For this refracted P-wave, we have derived, the equations of the elliptical-polarization trajectory. Following the elliptical-polarization trajectory, we calculated the effects of the rock anisotropic-parameters on the polarization state, with a Poincaré-sphere-like representation, for several varying media parameters. It is noted that the size, shape and initial phase angle of the elliptical-polarization trajectory are all depending the anisotropy media, as well as on the incident-angle. We expect that the findings from this paper would be applied to practical applications of seismic exploration.

  9. Attenuation of P-Waves by Wave-Induced Fluid Flow

    SciTech Connect

    Pride, S R; Berryman, J G

    2002-03-29

    Analytical expressions for three P-wave attenuation mechanisms in rocks are given and numerically-compared. The mechanisms are: (1) Biot loss, in which flow occurs at the scale of the wavelength between the peaks and troughs of a P wave; (2) squirt loss, in which flow occurs at the grain scale between microcracks the grains and the adjacent pores; and (3) mesoscopic loss, in which flow occurs at intermediate scales between the various lithological bodies that are present in an averaging volume of earth material. Each mechanism is of importance over different frequency bands. Typically, Biot loss is only important at the highest of ultrasonic frequencies (> 1 MHz), squirt-loss (when it occurs) is important in the range of 10 kHz to 1 MHz, while mesoscale loss dominates at the lower frequencies (<10 kHz) employed in seismology.

  10. Properties of skyrmions and multi-quanta vortices in chiral p-wave superconductors

    PubMed Central

    Garaud, Julien; Babaev, Egor

    2015-01-01

    Chiral p-wave superconducting state supports a rich spectrum of topological excitations different from those in conventional superconducting states. Besides domain walls separating different chiral states, chiral p-wave state supports both singular and coreless vortices also interpreted as skyrmions. Here, we present a numerical study of the energetic properties of isolated singular and coreless vortex states as functions of anisotropy and magnetic field penetration length. In a given chiral state, single quantum vortices with opposite winding have different energies and thus only one kind is energetically favoured. We find that with the appropriate sign of the phase winding, two-quanta (coreless) vortices are always energetically preferred over two isolated single quanta (singular) vortices. We also report solutions carrying more flux quanta. However those are typically more energetically expensive/metastable as compared to those carrying two flux quanta. PMID:26631985