The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform

Karl M Newell - One of the best experts on this subject based on the ideXlab platform.

  • Differential time- and frequency-Dependent Structure of postural sway and finger tremor in Parkinson's disease
    Neuroscience letters, 2008
    Co-Authors: Steven Morrison, Karl M Newell, Graham K. Kerr, Peter A. Silburn
    Abstract:

    The time- and frequency-Dependent patterns of standing balance centre of pressure (COP) and finger postural/resting tremor of 12 older individuals and eight age-matched Parkinsonian (PD) participants (on/off medication) were investigated. Tremor and COP data were analysed using measures of signal amplitude (RMS), time-Dependent Structure (approximate entropy, ApEn), time–frequency analysis and synchrony (Cross ApEn). Results showed that the PD individuals had significantly greater tremor amplitude and COP excursions in comparison to controls. Differences in the time-Dependent Structure were also observed between groups. In comparison to the elderly, the resting/postural tremor output of the PD subjects was more regular (lower ApEn). However, for the postural measures, a reciprocal pattern was observed with the COP being more complex (higher ApEn). All group differences were magnified when the PD individuals were off their medication. There was also greater synchrony between tremor and postural sway for the PD individuals, indicating a high degree of association between these motor outputs. These results are consistent with the view that the neural signal driving the enhanced limb tremor in PD is propagated throughout the motor system, consequently emerging within the postural sway dynamics. This commonality of motor output may be a contributing factor in the differential pattern in the dynamics of effector signal Structure in PD as a function of task.

  • Time-Dependent Structure in the discharge rate of human motor units.
    Clinical Neurophysiology, 2002
    Co-Authors: David E Vaillancourt, Lars Larsson, Karl M Newell
    Abstract:

    Abstract Objectives : The aim of this study was to examine the influence of visual and motor processes on the deterministic and stochastic Structure of force output and motor unit discharge variability. Methods : Young adult subjects produced continuous, isometric force at 3, 6, 12, and 24% of their maximal voluntary contraction at low and high visual gain levels through abduction of the index finger. Force and fine-wire intramuscular electromyography were recorded. Results : There was a linear increase in discharge irregularity with increases in the mean motor unit discharge rate (8–30Hz). Recurrence analysis showed that the percentage of deterministic Structure in discharge variability remained high, but decreased linearly with increased motor unit discharge rate. Surrogate analyses confirmed that the motor unit discharge variability was inconsistent with an uncorrelated and linearly correlated Gaussian noise process. Spectral analysis revealed that both the force output and the mean time-varying motor unit discharge time series had a dominant frequency of 0–2Hz. Visual feedback gain did not affect the individual motor unit discharge patterns. Conclusions : The motor unit discharge rate has deterministic time-Dependent Structure. The motor unit discharge rate is modulated at multiple time scales likely by pre- and post-synaptic induced fluctuations from spinal level pathways impinging on the motor neuron.

B. Badelek - One of the best experts on this subject based on the ideXlab platform.

  • spin asymmetry a1 d and the spin Dependent Structure function g1 d of the deuteron at low values of x and q 2
    Physics Letters B, 2007
    Co-Authors: Yu V Alexakhin, B. Badelek, Yu Alexandrov, G D Alexeev, A Amoroso, F Balestra, J Ball, G Baum, Y Bedfer, C Bernet
    Abstract:

    We present a precise measurement of the deuteron longitudinal spin asymmetry A(1)(d) and of the deuteron spin-Dependent Structure function g(1)(d) at Q(2) < 1 (GeV/c)(2) and 4 x 10(-5) < x < 2.5 x 10(-2) based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured A(1)(d) and g(1)(d) are found to be consistent with zero in the whole range of x. (c) 2007 Elsevier B.V. All rights reserved.

  • the deuteron spin Dependent Structure function g1d and its first moment
    Physics Letters B, 2007
    Co-Authors: Yu V Alexakhin, B. Badelek, Yu Alexandrov, G D Alexeev, M Alexeev, A Amoroso, F Balestra, J Ball, J Barth, Günter Baum
    Abstract:

    Abstract We present a measurement of the deuteron spin-Dependent Structure function g 1 d based on the data collected by the COMPASS experiment at CERN during the years 2002–2004. The data provide an accurate evaluation for Γ 1 d , the first moment of g 1 d ( x ) , and for the matrix element of the singlet axial current, a 0 . The results of QCD fits in the next to leading order (NLO) on all g 1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function ΔG positive or negative, which describe the data equally well. In both cases, at Q 2 = 3 ( GeV / c ) 2 the first moment of Δ G ( x ) is found to be of the order of 0.2–0.3 in absolute value.

  • Spin Dependent Structure function $g_1(x,Q^2)$ at low x and low $Q^2$
    arXiv: High Energy Physics - Phenomenology, 2003
    Co-Authors: B. Badelek
    Abstract:

    This is a review of experimental and phenomenological investigations of the nucleon spin Dependent Structure function $g_1$ at low values of $x$ and $Q^2$.

  • Spin Dependent Structure function g 1 at small x and small Q 2
    Journal of Physics G: Nuclear and Particle Physics, 1999
    Co-Authors: B. Badelek, J. Kwiecinski
    Abstract:

    The QCD improved parton model description of the spin Dependent Structure function g1(x,Q2) based on the unintegrated spin Dependent parton distributions is extended to the low Q2 region. Theoretical predictions are compared with the recent SMC data in the low x, low Q2 region.

  • the spin Dependent Structure function g1 x of the deuteron from polarized deep inelastic muon scattering
    Physics Letters B, 1997
    Co-Authors: D Adams, B. Adeva, A. Arvidson, B. Badelek, M. Ballintijn, G. Bardin, E. Arik, T Akdogan, D Bardin, Günter Baum
    Abstract:

    Abstract We present a new measurement of the virtual photon proton asymmetry A 1 p from deep inelastic scattering of polarized muons on polarized protons in the kinematic range 0.0008 x Q 2 2 . With this, the statistical uncertainty of our measurement has improved by a factor of 2 compared to our previous measurements. The spin-Dependent Structure function g 1 p is determined for the data with Q 2 > 1 GeV 2 . A perturbative QCD evolution in next-to-leading order is used to determine g 1 p ( x ) at a constant Q 2 . At Q 2 = 10 GeV 2 we find, in the measured range, ∫ 0.003 0.7 g 1 P (x) d x=0.139±0.006 ( stat ) ±0.008 ( syst ) ±0.006( evol ) . The value of the first moment Г 1 P = ∫ 0 1 g 1 p (x) d x of g 1 p depends on the approach used to describe the behaviour of g 1 p at low x . We find that the Ellis-Jaffe sum rule is violated. With our published result for Γ 1 d we confirm the Bjorken sum rule with an accuracy of ≈ 15% at the one standard deviation level.

Edward W Castner - One of the best experts on this subject based on the ideXlab platform.

  • temperature Dependent Structure of ionic liquids x ray scattering and simulations
    Faraday Discussions, 2012
    Co-Authors: Hemant K Kashyap, Cherry S Santos, Harsha V R Annapureddy, Sanjeeva N Murthy, Claudio J Margulis, Edward W Castner
    Abstract:

    In this article we determine the temperature-Dependent Structure of the tetradecyltrihexylphosphonium bis(trifluoromethylsulfonyl)amide ionic liquid using a combination of X-ray scattering and molecular dynamics simulations. As in many other room-temperature ionic liquids three characteristic intermolecular peaks can be detected in the Structure function S(q). A prepeak or first sharp diffraction peak is observed at about q = 0.42 A−1. Long range anion-anion correlations are the most important contributors to this peak. In all systems we have studied to date, this prepeak is a signature of solvation asymmetry. The peak in S(q) near q = 0.75 A−1 is the signature of ionic alternation and arises from the charge ordered separation of ions of the same charge. The most intense diffraction peak near q = 1.37 A−1 arises from short-range separation between ions of opposite charge combined with a significant contribution from cationic carbon-carbon interactions, indicating that cationic hydrophobic tails have significant contacts.

J. Kwiecinski - One of the best experts on this subject based on the ideXlab platform.

  • Spin Dependent Structure function g(1) at low x and low Q(2) - art. no. 014009
    Physical Review D, 2000
    Co-Authors: B. Badełek, J. Kiryluk, J. Kwiecinski
    Abstract:

    A theoretical description of the spin Dependent Structure function g(1)(x, Q(2)) in the region of low values of x and Q(2) is presented. It contains the vector meson dominance contribution and the QCD improved parton model suitably extended to the low Q(2

  • Spin Dependent Structure function g 1 at low x and low Q 2
    Physical Review D, 1999
    Co-Authors: B. Badełek, J. Kiryluk, J. Kwiecinski
    Abstract:

    Theoretical description of the spin Dependent Structure function g_1(x,Q^2) in the region of low values of x and Q^2 is presented. It contains the Vector Meson Dominance contribution and the QCD improved parton model suitably extended to the low Q^2 domain. Theoretical predictions are compared with the recent experimental data in the low x, low Q^2 region.

  • Spin Dependent Structure function g 1 at small x and small Q 2
    Journal of Physics G: Nuclear and Particle Physics, 1999
    Co-Authors: B. Badelek, J. Kwiecinski
    Abstract:

    The QCD improved parton model description of the spin Dependent Structure function g1(x,Q2) based on the unintegrated spin Dependent parton distributions is extended to the low Q2 region. Theoretical predictions are compared with the recent SMC data in the low x, low Q2 region.

  • Spin Dependent Structure Function $g_1$ at Low $x$
    arXiv: High Energy Physics - Phenomenology, 1998
    Co-Authors: J. Kwiecinski
    Abstract:

    Theoretical expectations concerning small $x$ behaviour of the spin Dependent Structure function $g_1$ are summarised. This includes discussion of the Regge pole model predictions and of the double $ln^2(1/x)$ effects implied by perturbative QCD. The quantitative implementation of the latter is described within the unified scheme incorporating both Altarelli-Parisi evolution and the double $ln^2(1/x)$ resummation. The double $ln^2(1/x)$ effects are found to be important in the region of $x$ which can possibly be probed at HERA. Predictions for the polarized gluon distribution $\Delta G(x,Q^2)$ at low $x$ are also given.

Günter Baum - One of the best experts on this subject based on the ideXlab platform.

  • the deuteron spin Dependent Structure function g1d and its first moment
    Physics Letters B, 2007
    Co-Authors: Yu V Alexakhin, B. Badelek, Yu Alexandrov, G D Alexeev, M Alexeev, A Amoroso, F Balestra, J Ball, J Barth, Günter Baum
    Abstract:

    Abstract We present a measurement of the deuteron spin-Dependent Structure function g 1 d based on the data collected by the COMPASS experiment at CERN during the years 2002–2004. The data provide an accurate evaluation for Γ 1 d , the first moment of g 1 d ( x ) , and for the matrix element of the singlet axial current, a 0 . The results of QCD fits in the next to leading order (NLO) on all g 1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function ΔG positive or negative, which describe the data equally well. In both cases, at Q 2 = 3 ( GeV / c ) 2 the first moment of Δ G ( x ) is found to be of the order of 0.2–0.3 in absolute value.

  • the spin Dependent Structure function g1 x of the deuteron from polarized deep inelastic muon scattering
    Physics Letters B, 1997
    Co-Authors: D Adams, B. Adeva, A. Arvidson, B. Badelek, M. Ballintijn, G. Bardin, E. Arik, T Akdogan, D Bardin, Günter Baum
    Abstract:

    Abstract We present a new measurement of the virtual photon proton asymmetry A 1 p from deep inelastic scattering of polarized muons on polarized protons in the kinematic range 0.0008 x Q 2 2 . With this, the statistical uncertainty of our measurement has improved by a factor of 2 compared to our previous measurements. The spin-Dependent Structure function g 1 p is determined for the data with Q 2 > 1 GeV 2 . A perturbative QCD evolution in next-to-leading order is used to determine g 1 p ( x ) at a constant Q 2 . At Q 2 = 10 GeV 2 we find, in the measured range, ∫ 0.003 0.7 g 1 P (x) d x=0.139±0.006 ( stat ) ±0.008 ( syst ) ±0.006( evol ) . The value of the first moment Г 1 P = ∫ 0 1 g 1 p (x) d x of g 1 p depends on the approach used to describe the behaviour of g 1 p at low x . We find that the Ellis-Jaffe sum rule is violated. With our published result for Γ 1 d we confirm the Bjorken sum rule with an accuracy of ≈ 15% at the one standard deviation level.

  • a new measurement of the spin Dependent Structure function g1 x of the deuteron
    Physics Letters B, 1995
    Co-Authors: D Adams, B. Adeva, A. Arvidson, B. Badelek, M. Ballintijn, G. Bardin, Günter Baum, Per Berglund, E. Arik, Latchezar Betev
    Abstract:

    Abstract We present a new measurement of the spin-Dependent Structure function g 1 d of the deuteron in deep inelastic scattering of 190 GeV polarised muons on polarised deuterons, in the kinematic range 0.003 x 2 Q 2 2 . This Structure function is found to be negative at small x . The first moment Γ 1 d =∫ 0 1 g 1 d d x evaluated at Q 0 2 = 10 GeV 2 is 0.034 ± 0.009 (stat.) ± 0.006 (syst.). This value is below the Ellis-Jaffe sum rule prediction by three standard deviations. Using our earlier determination of Γ 1 p , we obtain Γ 1 p − Γ 1 n = 0.199 ± 0.038 which agrees with the Bjorken sum rule.

  • Measurement of the spin-Dependent Structure function g 1 ( x) of the proton
    Physics Letters B, 1994
    Co-Authors: D. L. Adams, B. Adeva, A. Arvidson, B. Badelek, M. Ballintijn, G. Bardin, Günter Baum, Per Berglund, E. Arik, Latchezar Betev
    Abstract:

    We have measured the spin-Dependent Structure function g1p of the proton in deep inelastic scattering of polarized muons off polarized protons, in the kinematic range 0.003 < x < 0.7 and 1 GeV2 < Q2 < 60 GeV2. Its first moment, ∫01g1p(x)dx, is found to be 0.136±0.011 (stat.)± 0.011 (syst.) at Q2 = 10GeV2. This value is smaller than the prediction of the Ellis-Jaffe sum rule by two standard deviations, and is consistent with previous measurements. A combined analysis of all available proton, deuteron and neutron data confirms the Bjorken sum rule to within 10% of the theoretical valu

  • measurement of the spin Dependent Structure function g1 x of the deuteron
    Physics Letters B, 1993
    Co-Authors: B. Adeva, Salahuddin Ahmad, A. Arvidson, B. Badelek, M. Ballintijn, G. Bardin, Günter Baum, Per Berglund
    Abstract:

    We have measured the spin-Dependent Structure function $g_1~p$ of the proton in deep inelastic scattering of polarized muons off polarized protons, in the kinematic range $0.003sum rule by two standard deviations, and is consistent with previous measurements. A combined analysis of all available proton, deuteron and neutron data confirms the Bjorken sum rule to within $10\%$ of the theoretical value.