股骨近端防旋髓内钉治疗高龄股骨转子间骨折

因子模型在刻画因子之间的相互关系以及因子与观测变量之间的关联性具有重要作用.在实际应用中,观测数据往往呈现出时序变异多峰、偏态等特性.本文将经典的潜变量模型延伸到非齐次隐马尔可夫潜变量模型,建立了极大似然统计分析程序.经验结果展示所建立的统计程序是有效的.     

腰丛+坐骨神经阻滞麻醉对口服阿司匹林股骨转子间骨折老年患者的效果观察

目的 探讨腰丛+ 坐骨神经阻滞麻醉在口服阿司匹林股骨转子间骨折老年患者中的应用效果。方法 拟行手术治疗的股骨转子间骨折老年患者60 例,分为实验组（术前口服阿司匹林）和对照组（术前无服用阿司匹林）,每组各30 例。实验组患者采用腰丛+ 坐骨神经阻滞麻醉,对照组患者采用腰麻- 硬膜外联合麻醉。两组患者术后48h 内均给予帕瑞昔布钠针40mg 静脉注射和盐酸布桂嗪针0.1g 肌肉注射,1 次/12h。记录两组患者围麻醉期血压和心率的变化,及术后静息状态下视觉模拟疼痛评分和恶心、呕吐等麻醉不良反应的发生率。结果 实验组患者围麻醉期血压、心率较对照组更平稳,术后疼痛评分与对照组比较均无统计学差异（均P＞0.05）;实验组术后不良反应发生率较对照组明显降低（P＜0.05）。结论 腰丛+ 坐骨神经阻滞麻醉对口服阿司匹林股骨转子间骨折的老年患者安全、有效,联合术后定时镇痛,可改善患者术后疼痛并降低术后麻醉不良反应发生率。     

克氏针联合外固定支架治疗桡骨远端不稳定骨折疗效分析

目的探讨克氏针联合外固定支架治疗桡骨远端不稳定骨折的临床疗效.方法选取桡骨远端不稳定骨折患者120例,其中采用经皮克氏针联合外固定支架治疗60例(观察组),采用切开复位锁定接骨板系统内固定治疗60例(对照组).比较两组患者术中出血量及手术时间,术后切口愈合时间、骨折愈合时间以及并发症发生情况.结果观察组患者手术时间、切口愈合时间、骨折愈合时间均明显短于对照组、术中出血量显著少于对照组,差异均有统计学意义(P<0.05或0.01).两组患者术后腕关节功能及复位质量均无明显差异(均P>0.05).观察组患者术后仅创伤性关节炎发生率明显低于对照组(P<0.05),两组患者其他并发症发生率的差异均无统计学意义(均P>0.05).结论克氏针联合外固定支架治疗桡骨远端不稳定骨折,具有创伤小、岀血量少,缩短手术时间、伤口愈合时间及骨折愈合时间,恢复快、功能良好、术后并发症发生率低等优点,值得临床推广.     

Invertibility of systems with unstable zero dynamics

We consider the problem of robust inversion of an uncertain dynamical system with unstable zero dynamics. The solution of the problem is reduced to estimating in real time the bounded solution of an unstable linear differential equation. Estimation algorithms are proposed for one- and two-output systems. Convergence of the inversion algorithms is assessed and the effect of observation errors on the algorithms, i.e., their robustness, is investigated.Translated from Nelineinaya Dinamika i Upravlenie, No. 2, pp. 33–40, 2002.     

Classification of Morse-Smale diffeomorphisms with one-dimensional set of unstable separatrices

Let M ⁿ be a closed orientable manifold of dimension n > 3. We study the class G ₁(M ⁿ ) of orientation-preserving Morse-Smale diffeomorphisms of M ⁿ such that the set of unstable separatrices of any f ∈ G ₁(M ⁿ ) is one-dimensional and does not contain heteroclinic intersections. We prove that the Peixoto graph (equipped with an automorphism) is a complete topological invariant for diffeomorphisms of class G ₁(M ⁿ ), and construct a standard representative for any class of topologically conjugate diffeomorphisms.     

Hierarchical decomposition of domains with fractures

We consider the efficient and robust numerical solution of elliptic problems with jumping coefficients occurring on a network of thin fractures. We present an iterative solution concept based on a hierarchical separation of the fractures and the surrounding rock matrix. Upper estimates for the convergence rates are independent of the width of the fractures and of the jumps of the coefficients. Inexact solution of the local subproblems is also considered. The theoretical results are illustrated by numerical experiments.

     

Stabilization of unstable stationary points in equations with delayed argument

We solve the problem of localization and stabilization of an unstable stationary point of a nonlinear system of ordinary differential equations (ODE) with a delayed argument for parameter values when the ODE system has chaotic dynamics. Translated from Nelineinaya Dinamika i Upravlenie, pp. 133–141, 1999.     

On the numerical approximation of unstable minimal surfaces with polygonal boundaries

Summary. This work is concerned with the approximation and the numerical computation of polygonal minimal surfaces in . Polygonal minimal surfaces correspond to the critical points of Shiffman's function . Since this function is analytic, polygonal minimal surfaces can be characterized by means of the second derivative of . We present a finite element approximation of quasiminimal surfaces together with an error estimate. In this way we obtain discrete approximations of and of . In particular we prove that the discrete functions converge uniformly on certain compact subsets. This will be the main tool for proving existence and convergence of discrete minimal surfaces in neighbourhoods of non-degenerate minimal surfaces. In the numerical part of this paper we compute numerical approximations of polygonal minimal surfaces by use of Newton's method applied to . Received October 27, 1994     

Stability of switched nonlinear time-delay systems with stable and unstable subsystems

This paper investigates the stability of switched nonlinear time-delay systems with stable and unstable subsystems. Several stability criteria are presented by resorting to novel inequality technique and average dwell time approach, which relax the assumptions that all subsystem matrices are commutative pairwise and Hurwitz stable. Finally, two numerical examples are provided to illustrate the effectiveness of the theoretical results.