The effect of transcranial direct current stimulation on perception of effort in an isolated isometric elbow flexion task

This is the author's manuscript as accepted for publication in Motor Control. The final published article is available from the link below, copyright @ 2013 Human Kinetics.The purported ergogenic actions of transcranial direct current stimulation (tDCS) applied to motor cortex (M1) on force production and perception of effort were investigated using a 10-item numerical rating scale (0–10 NRS) in nonfatiguing bouts of a force-matching task utilizing isometric elbow flexion. Using a crossover design, 12 healthy volunteers received sham, anodal, and cathodal tDCS randomly for 10 min (1.5 mA, 62 ìA/cm2) to the left M1 in a double-blind manner. Cor- ticospinal excitability changes were also monitored using transcranial magnetic stimulation (TMS) with surface electromyography (sEMG) to monitor both motor evoked potentials (MEPs) and force-EMG from right m. biceps brachii and m. brachioradialis brachii. No significant differences between the verum and sham stimulation were obtained for elbow flexion maximum voluntary force, perception of effort, or sEMG. There were also no significant differences in MEP changes for the types of tDCS, which is consistent with reports that tDCS excitability effects are diminished during ongoing cognitive and motor activities.Brunel Universit

Anti-symmetric motion of a pre-stressed incompressible elastic layer near shear resonance

A two-dimensional model is derived for anti-symmetric motion in the vicinity of the shear resonance frequencies in a pre-stressed incompressible elastic plate. The method of asymptotic integration is used and a second-order solution, for infinitesimal displacement components and incremental pressure, is obtained in terms of the long-wave amplitude. The leading-order hyperbolic governing equation for the long-wave amplitude is observed to be not wave-like for certain pre-stressed states, with time and one of the in-plane spatial variables swapping roles. This phenomenon is shown to be intimately related to the possible existence of negative group velocity at low wave number, i.e. in the vicinity of shear resonance frequencies

A two-dimensional model for extensional motion of a pre-stressed incompressible elastic layer near cut-of frequencies

A two-dimensional model for extensional motion of a pre-stressed incompressible elastic layer near its cut-off frequencies is derived. Leading-order solutions for displacement and pressure are obtained in terms of the long wave amplitude by direct asymptotic integration. A governing equation, together with corrections for displacement and pressure, is derived from the second-order problem. A novel feature of this (two-dimensional) hyperbolic governing equation is that, for certain pre-stressed states, time and one of the two (in-plane) spatial variables can change roles. Although whenever this phenomenon occurs the equation still remains hyperbolic, it is clearly not wave-like. The second-order solution is completed by deriving a refined governing equation from the third-order problem. Asymptotic consistency, in the sense that the dispersion relation associated with the two-dimensional model concurs with the appropriate order expansion of the three-dimensional relation at each order, is verified. The model has particular application to stationary thickness vibration of, or transient response to high frequency shock loading in, thin walled bodies

m-FISH analysis reveals complexity of chromosome aberrations in individuals occupationally exposed with internal plutonium: A pilot study to assess the relevance of complex aberrations as biomarkers of exposure to high-LET α particles

We recently demonstrated that a significant proportion of apparently stable insertions induced after exposure to a mean of 1 α particle/cell, detected using 3-colour FISH, were part of larger unstable complexes when visualised by 24-colour FISH. Interestingly, regardless of the long-term persistence capability of the cell, the complexity of each α particle-induced complex appeared to be specific to the nuclear traversal of a single -particle. To assess whether aberrations of a similar complexity are observed in vivo and also to examine the usefulness of detecting such aberrations as a biomarker of chronic exposure to α particles, we have carried out a limited pilot study of Russian workers with large body burdens of -particle emitting plutonium (Pu). We found unstable cells containing non-transmissible complex aberrations in all of the Pu exposed subjects analysed by m-FISH. In addition, all of the complexes seen were consistent with those previously observed in vitro. Non-transmissible complex aberrations were more common than transmissible-type complexes, consistent with on-going/chronic exposure and insertions were dominant features of both type of complex. Accordingly, this preliminary study supports the proposal that aberration complexity and non-transmissibility are the major cytogenetic features of α particle exposure that could potentially be exploited as a specific indicator of chronic exposures to high-LET α particles

On rational boundary conditions for higher-order long-wave models

Higher-order corrections to classical long-wave theories enable simple and efficient modelling of the onset of wave dispersion and size effects produced by underlying micro-structure. Since such models feature higher spatial derivatives, one needs to formulate additional boundary conditions when confined to bounded domains. There is a certain controversy associated with these boundary conditions, because it does not seem possible to justify their choice by purely physical considerations. In this paper an asymptotic model for onedimensional chain of particles is chosen as an exemplary higher-order theory. We demonstrate how the presence of higher-order derivative terms results in the existence of non-physical “extraneous” boundary layer-type solutions and argue that the additional boundary conditions should generally be formulated to eliminate the contribution of these boundary layers into the averaged solution. Several new methods of deriving additional boundary conditions are presented for essential boundary. The results are illustrated by numerical examples featuring comparisons with an exact solution for the finite chain

DISTRIBUTION OF INTEGER LATTICE POINTS IN A BALL CENTRED AT A DIOPHANTINE POINT

We study the variance of the fluctuations in the number of lattice points in a ball and in a thin spherical shell of large radius centred at a Diophantine point

Cocliques of maximal size in the prime graph of a finite simple group

In this paper we continue our investgation of the prime graph of a finite simple group started in http://arxiv.org/abs/math/0506294 (the printed version appeared in [1]). We describe all cocliques of maximal size for all finite simple groups and also we correct mistakes and misprints from our previous paper. The list of correction is given in Appendix of the present paper.Comment: published version with correction

Multigrid for propagators of staggered fermions in four-dimensional SU(2)SU(2) gauge fields

Multigrid (MG) methods for the computation of propagators of staggered fermions in non-Abelian gauge fields are discussed. MG could work in principle in arbitrarily disordered systems. The practical variational MG methods tested so far with a ``Laplacian choice'' for the restriction operator are not competitive with the conjugate gradient algorithm on lattices up to $18^4$. Numerical results are presented for propagators in $SU(2)$ gauge fields.Comment: 4 pages, 3 figures (one LaTeX-figure, two figures appended as encapsulated ps files); Contribution to LATTICE '92, requires espcrc2.st