Analysis of cases of self-displaced and healed shunt of arachnoid cyst and review of literature

Objective:To investigate the causes,pathogenesis and prognosis of shunt displacement in arachnoid cyst.Methods:Retrospective analysis was made on the case of the left frontal top arachnoid cyst peritoneal shunt self-extraneous and cured in our hospital in November 2019.Combined with literature review,the treatment and prognosis of shunt displacement after arachnoid cyst peritoneal shunt were discussed.Results:Arachnoid cyst disappeared children heal,clinical symptoms improved,wipe out the shift shunt,literature review arachnoid cyst peritoneal shunt tube shift and recover rare,mainly for the shunt tube distal displacement,falling in the scrotum,emergence anus,and shift to the chest,or even a heart,required reoperation processing,timely deal with good prognosis.Conclusion:Arachnoid cyst peritoneal shunt may be an effective method for the treatment of cerebral convex arachnoid cyst in children,and it also suggests that the shunt tube can be removed after the disappearance of cerebral convex arachnoid cyst.Shunt tube displacement is rare in clinic and needs timely surgical treatment.

Parallel Multicore CSB Format and Its Sparse Matrix Vector Multiplication

Sparse Matrix Vector Multiplication (SpMV) is one of the most basic problems in scientific and engineering computations. It is the basic operation in many realms, such as solving linear systems or eigenvalue problems. Nowadays, more than 90 percent of the world’s highest performance parallel computers in the top 500 use multicore architecture. So it is important practically to design the efficient methods of computing SpMV on multicore parallel computers. Usually, algorithms based on compressed sparse row (CSR) format suffer from a number of nonzero elements on each row so hardly as to use the multicore structure efficiently. Compressed Sparse Block (CSB) format is an effective storage format which can compute SpMV efficiently in a multicore computer. This paper presents a parallel multicore CSB format and SpMV based on it. We carried out numerical experiments on a parallel multicore computer. The results show that our parallel multicore CSB format and SpMV algorithm can reach high speedup, and they are highly scalable for banded matrices.

Interpretation of thermal dependence of magnetic aftereffect for magnetic nanocomposite with slow decay rates

A new experimental characterization is presented of time-,field-,and temperature-dependent dynamic effects in magnetization of a nanocomposite which displays slow decay.Field and temperature variations of irreversible susceptibility,χirr,decay coefficient,S,fluctuation field,hf,and activation volume,V,have been calculated for the nanocomposite sample(Co_(80)Ni_(20))using a recently developed modified Preisach–Arrhenius(MPA)model.The sample is composed of non-interacting nanoparticles having negligible reversible magnetization.Non-Arrhenius behavior is observed in both the maximum decay coefficient,Smax,and the fluctuation field,hf,as a function of temperature T.The peak of both temperature curves are identical and occur at a critical temperature Tk of∼50 K,which agrees with our experimental results.Based on the effect of a temperature-dependent chemical potential on energy barrier,hf is studied for T<Tk and T≥Tk,respectively.A more complete MPA model that can predict the magnetization as function of time,field and temperature for a magnetic material with slow decay rates is proposed.This model uses a multi-variable analytical formula,m(ln(t),H,T),which incorporates the characteristic parameters.