Convergence of a preconditioned iterative method for H-matrices

AbstractIn this paper, we consider a preconditioned iterative method for solving the linear system Ax = b, which is a generalization of a method proposed in Kotakemori et al. [3] and prove its convergence for the case when A is an H-matrix

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

Ultrasonographic observation of the healing process in the gap after a Ponseti-type Achilles tenotomy for idiopathic congenital clubfoot at two-year follow-up

AbstractBackgroundPonseti management usually requires Achilles tenotomy during the final stage of serial casting. However, we lack a good understanding of the sequential tendon healing process after tenotomy in the Ponseti bracing protocol. The purpose of this study was to clarify the ultrasonographic process of tendon healing in the gap for up to twoyears after Ponseti-type Achilles tenotomy in patients with clubfeet.MethodsWe conducted an ultrasonographic study to clarify the sequential changes in gap healing for up to twoyears after tenotomy. The subjects were 23 patients with 33 clubfeet. Achilles tenotomy was performed at mean 10.4 (8–16) weeks after birth. Dynamic and static ultrasonography was performed before tenotomy and at 1, 2, 3, 4, 6, 8, and 12weeks as well as at 4, 6, 12, 18, and 24months after tenotomy.ResultsContinuity and gliding were noted within fourweeks. The united portion continued to thicken for up to threemonths after tenotomy. Starting from the fourth month, the healed portion began to lose its thickness, and this process continued into the sixth month. At oneyear, the thickness of the tendon did not differ much from that of the tendon on the opposing foot. In cases where patients had clubfoot on both feet and underwent simultaneous tenotomies, measurement of the tendons could not be accurately compared. At twoyears after tenotomy, slight irregularity of the internal structure persisted when compared with the unaffected foot. In addition, clinical and X-ray findings were evaluated simultaneously, and no recurrence was confirmed.ConclusionsTo our knowledge, our results are the first to describe the process of gap healing in the tendon after tenotomy up to and beyond twoyears, as recommended in the Ponseti bracing protocol.Level of evidence IV

Peroxynitrite-induced hemolysis of human erythrocytes and its inhibition by antioxidants

AbstractIt was found that human erythrocytes underwent hemolysis when incubated with peroxynitrite at 37°C under air. The extent of hemolysis increased with increasing peroxynitrite concentration and decreasing hematocrit. The peroxynitrite-induced hemolysis was suppressed only partially by a radical scavenging antioxidant such as uric acid and Trolox, a water-soluble vitamin E analogue, but reduced glutathione, N-acetylcysteine and albumin efficiently inhibited the hemolysis. A selenium-containing organic compound, ebselen, also suppressed the hemolysis. On the other hand, nitric oxide and superoxide generated concomitantly from 3-morpholinosydnonimine (SIN-1) did not induce appreciable hemolysis, while it converted hemoglobin to methemoglobin extensively

Bryosphere within an Antarctic moss pillar

第6回極域科学シンポジウム分野横断セッション：[IB2] 地球環境変動の解析と地球生命システム学の構築11月19日（木）　統計数理研究所 セミナー室1（D305

シンエコー ドップラーホウ ニヨル ソウボウベンリン セッカイカ ニ トモナウ ベンリン キョウサク ノ ジュウショウド ヒョウカ

Recently, mitral annular calcification (MAC) is a common finding with increasing of elderly orrenal failure patients. Mitral stenosis secondary to MAC is not rarely observed. Pressure halftime method by continuous wave Doppler echocardiography is often used to evaluate the severityof the stenotic mitral valve due to MAC. But, the method for calculating correct mitral orifice areais not established. We performed transthoracic Doppler echocardiography and cardiac catheterizationin 15 patients with rheumatic mital stenosis and 10 with mitral stenosis due to MAC, and calculatedthe severity of the mitral stenosis by pressure half time (PHT), continuity equation methods andGorlin formula. Pulsed tissue Doppler imaging methods were used for evaluating left ventricular(LV) early diastolic wall motion velocities. Results were as follows. 1) The mitral orifice areas determinedby PHT method were lower than those by continuity equation methods or Gorlin formulain patients with mitral stenosis due to MAC, and significant correlation was observed in rheumaticmital stenosis between the mitral orifice areas obtained by PHT and continuity equation methods,but not in mitral stenosis due to MAC. 2) The peak early diastolic LV myocardial velocities alonglong and short axes decreased significantly in mitral stenosis due to MAC than those in rheumaticmital stenosis. In conclusion, as mitral orfice area determined from PHT method is strongly influencedby early diastolic LV dysfunction in mitral stenosis due to MAC, continuity equation methodshould be recommended

Neuroprotective effect of a new DJ-1-binding compound against neurodegeneration in Parkinson's disease and stroke model rats

<p>Abstract</p> <p>Background</p> <p>Parkinson's disease (PD) and cerebral ischemia are chronic and acute neurodegenerative diseases, respectively, and onsets of these diseases are thought to be induced at least by oxidative stress. PD is caused by decreased dopamine levels in the substantia nigra and striatum, and cerebral ischemia occurs as a result of local reduction or arrest of blood supply. Although a precursor of dopamine and inhibitors of dopamine degradation have been used for PD therapy and an anti-oxidant have been used for cerebral ischemia therapy, cell death progresses during treatment. Reagents that prevent oxidative stress-induced cell death are therefore necessary for fundamental therapies for PD and cerebral ischemia. DJ-1, a causative gene product of a familial form of PD, PARK7, plays roles in transcriptional regulation and anti-oxidative stress, and loss of its function is thought to result in the onset of PD. Superfluous oxidation of cysteine at amino acid 106 (C106) of DJ-1 renders DJ-1 inactive, and such oxidized DJ-1 has been observed in patients with the sporadic form of PD.</p> <p>Results</p> <p>In this study, a compound, comp-23, that binds to DJ-1 was isolated by virtual screening. Comp-23 prevented oxidative stress-induced death of SH-SY5Y cells and primary neuronal cells of the ventral mesencephalon but not that of DJ-1-knockdown SH-SY5Y cells, indicating that the effect of the compound is specific to DJ-1. Comp-23 inhibited the production of reactive oxygen species (ROS) induced by oxidative stress and prevented excess oxidation of DJ-1. Furthermore, comp-23 prevented dopaminergic cell death in the substantia nigra and restored movement abnormality in 6-hydroxyldopamine-injected and rotenone-treated PD model rats and mice. Comp-23 also reduced infarct size of cerebral ischemia in rats that had been induced by middle cerebral artery occlusion. Protective activity of comp-23 seemed to be stronger than that of previously identified compound B.</p> <p>Conclusions</p> <p>The results indicate that comp-23 exerts a neuroprotective effect by reducing ROS-mediated neuronal injury, suggesting that comp-23 becomes a lead compound for PD and ischemic neurodegeneration therapies.</p

On the Numerical Analysis of Elliptic Boundary Value Problems by the Successive Over relaxation Method (Report 1)

The successive over relaxation method is an effective iterative method for solving the difference analogue of an elliptic partial differential equation. But its main difficulty is that the optimum relaxation factor for any given problem can not usually be found prior to getting the solution. We^ have proposed an empirical new method, practical successive over relaxation method, for solving the Dirichlet problem. This computational method was named NIKI\u27s method by Radlley et al.^3. In this paper, we describe the proposed method and report the results of it and two other methods of successive over relaxation method by applying them to same problems

Evaluation of 14 questions detecting malnutrition in newly hospitalized patients

Malnutrition of patients is an important factor of poor prognosis and outcome and long stay in hospital. Nutrition screening is of course necessary for detecting underand malnutrition. However, appropriate rapid and easy screening tools for only acute and emergent hospitalized patients are not known. In this study, 14 questions composed with reported and new items were prepared and the utility of those questions for detecting malnutrition in novel hospitalized patients was evaluated. Combined questions on disturbance of swallowing, diarrhea and fever, and also on ageing, food intake and history of fall are very important for detecting malnutrition in newly hospitalized patients, although further study will be absolutely required