An extended GS method for dense linear systems

AbstractDavey and Rosindale [K. Davey, I. Rosindale, An iterative solution scheme for systems of boundary element equations, Internat. J. Numer. Methods Engrg. 37 (1994) 1399–1411] derived the GSOR method, which uses an upper triangular matrix Ω in order to solve dense linear systems. By applying functional analysis, the authors presented an expression for the optimum Ω. Moreover, Davey and Bounds [K. Davey, S. Bounds, A generalized SOR method for dense linear systems of boundary element equations, SIAM J. Comput. 19 (1998) 953–967] also introduced further interesting results. In this note, we employ a matrix analysis approach to investigate these schemes, and derive theorems that compare these schemes with existing preconditioners for dense linear systems. We show that the convergence rate of the Gauss–Seidel method with preconditioner PG is superior to that of the GSOR method. Moreover, we define some splittings associated with the iterative schemes. Some numerical examples are reported to confirm the theoretical analysis. We show that the EGS method with preconditioner PG(γopt) produces an extremely small spectral radius in comparison with the other schemes considered

Trimeric structure and conformational equilibrium of M-ficolin fibrinogen-like domain

The crystal structure and ligand-binding study of M-ficolin provides an insight into its discrimination mechanism between self and non-self

On the diagonally dominant ratio

It is well known that if the coefficient matrix is a generalized diagonally dominant matrix, then the Jacobi and the Gauss-Seidel methods converge. We know in our experiments that the number of iteration of these iterative methods is inveresely proportional to the degree of diagonal dominance of the coefficient matrix. In this paper, our is to present the definition of the diagonally dominant ratio as the degree of the convergence rate, and we define the diagonal dominator to improve the diagonally dominant ratio

Influence of Visual Stimulation-Induced Passive Reproduction of Motor Images in the Brain on Motor Paralysis After Stroke

Finger flexor spasticity, which is commonly observed among patients with stroke, disrupts finger extension movement, consequently influencing not only upper limb function in daily life but also the outcomes of upper limb therapeutic exercise. Kinesthetic illusion induced by visual stimulation (KINVIS) has been proposed as a potential treatment for spasticity in patients with stroke. However, it remains unclear whether KINVIS intervention alone could improve finger flexor spasticity and finger extension movements without other intervention modalities. Therefore, the current study investigated the effects of a single KINVIS session on finger flexor spasticity, including its underlying neurophysiological mechanisms, and finger extension movements. To this end, 14 patients who experienced their first episode of stroke participated in this study. A computer screen placed over the patient’s forearm displayed a pre-recorded mirror image video of the patient’s non-paretic hand performing flexion–extension movements during KINVIS. The position and size of the artificial hand were adjusted appropriately to create a perception that the artificial hand was the patient’s own. Before and after the 20-min intervention, Modified Ashworth Scale (MAS) scores and active range of finger extension movements of the paretic hand were determined. Accordingly, MAS scores and active metacarpophalangeal joint extension range of motion improved significantly after the intervention. Moreover, additional experimentation was performed using F-waves on eight patients whose spasticity was reduced by KINVIS to determine whether the same intervention also decreased spinal excitability. Our results showed no change in F-wave amplitude and persistence after the intervention. These results demonstrate the potential clinical significance of KINVIS as a novel intervention for improving finger flexor spasticity and extension movements, one of the most significant impairments among patients with stroke. The decrease in finger flexor spasticity following KINVIS may be attributed to neurophysiological changes not detectable by the F-wave, such as changes in presynaptic inhibition of Ia afferents. Further studies are certainly needed to determine the long-term effects of KINVIS on finger spasticity, as well as the neurophysiological mechanisms explaining the reduction in spasticity

Ferromagnetism in a Hubbard model for an atomic quantum wire: a realization of flat-band magnetism from even-membered rings

We have examined a Hubbard model on a chain of squares, which was proposed by Yajima et al as a model of an atomic quantum wire As/Si(100), to show that the flat-band ferromagnetism according to a kind of Mielke-Tasaki mechanism should be realized for an appropriate band filling in such a non-frustrated lattice. Reflecting the fact that the flat band is not a bottom one, the ferromagnetism vanishes, rather than intensified, as the Hubbard U is increased. The exact diagonalization method is used to show that the critical value of U is in a realistic range. We also discussed the robustness of the magnetism against the degradation of the flatness of the band.Comment: misleading terms and expressions are corrected, 4 pages, RevTex, 5 figures in Postscript, to be published in Phys. Rev. B (rapid communication

Outcome of hospitalised heart failure in Japan and the United Kingdom stratified by plasma N-terminal pro-B-type natriuretic peptide

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Background: Mortality subsequent to a hospitalisation for heart failure is reported to be much lower in Japan than in the United Kingdom (UK). This could reflect differences in disease severity or in management. Accordingly, we directly compared patient backgrounds and outcomes between Japan and UK. Methods: Consecutive patients admitted to academic hospitals in the UK and Japan with heart failure had a common set of variables, including plasma concentrations of N-terminal pro-B-type natriuretic peptide (NT-proBNP), collected during admission. Mortality during hospitalisations, at 90 and 180 days was recorded and stratified by quintile of NT-proBNP. Results: Overall, 935 patients were enrolled; 197 from UK and 738 from Japan. Median (interquartile range) age [UK: 78 (71–88) vs. Japan: 78 (70–84) years; p = 0.947], glomerular filtration rate [UK: 49 (34–68) vs. Japan: 49 (33–65) ml/min/1.73 m2; p = 0.209] and plasma NT-proBNP [UK: 4957 (2278–10,977) vs. Japan: 4155 (1972–9623) ng/l; p = 0.186] were similar, but systolic blood pressure was lower in the UK [118 (105–131) vs. 137 (118–159) mmHg; p < 0.001]. Patients with a higher plasma NT-proBNP had a worse prognosis in both countries; in-hospital and post-discharge mortality rates were higher in the UK even after adjusting for prognostic variables including NT-proBNP. Conclusions: This analysis suggests that either unobserved differences in patient characteristics or differences in care (formal or informal) rather than greater heart failure severity may account for the worse outcome of heart failure in the UK compared to Japan