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31.
OBJECTIVE: The initially well-fixed implants of total hip replacement (THR) are in the long-term subject to aseptic loosening. Many cytokines can contribute to osteolysis due to osteoclast recruitment and/or activation. However, in this respect tumor necrosis factor-alpha (TNF-alpha) plays a pivotal role, because it upregulates interleukin-1 and 6 and granulocyte-macrophage colony stimulating factor. The aim of this study was to assess the eventual presence, cellular localization and extent of expression of TNF-alpha in the synovial-like membrane at the implant or at the cement to bone interface compared to control synovial membrane. METHODS: Twenty samples from the synovial-like membrane of the periprosthetic tissues were compared to control samples. TNF-alpha containing cells were visualized using an avidin-biotin-peroxidase complex (ABC) method and analyzed by light microscopy, double labelling and image analysis. RESULTS: TNF-alpha was found in the periprosthetic tissues in fibroblasts and vascular endothelial cells, but mainly in the macrophages was it found to coincide with areas containing implant-derived debris. TNF-alpha containing cells were more numerous in the synovial-like membrane in the interface tissue from the proximal stem area (2816 +/- 318 cells) than in the control synovial membrane (565 +/- 93 cells, p < 0.01). Interestingly, similarly high TNF-alpha expression (3452 +/- 582 cells) was also seen in the synovial-like membrane of the pseudocapsule. CONCLUSION: These findings suggest that the foreign body-type host reaction caused by THR is characterized by the high expression of TNF-alpha. Because such expression occurred in the interface tissue between the implant and surrounding bone, TNF-alpha, due to its pivotal direct and indirect role in the activation and recruitment of osteoclasts, may contribute to periprosthetic osteolysis and to the loosening of THR.  相似文献   
32.
This paper presents a recurrent neural-network model for solving a special class of general variational inequalities (GVIs), which includes classical VIs as special cases. It is proved that the proposed neural network (NN) for solving this class of GVIs can be globally convergent, globally asymptotically stable, and globally exponentially stable under different conditions. The proposed NN can be viewed as a modified version of the general projection NN existing in the literature. Several numerical examples are provided to demonstrate the effectiveness and performance of the proposed NN.  相似文献   
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小口径弹道炮在使用初期,弹道特性值偏高,影响产品的验收和标准弹的鉴选.该文用膛阻理论解释弹道炮使用的各个时期的弹道特性变化,并介绍了“光膛”射击后,在弹道曲线下降段进行产品验收以及标准弹鉴选中的实际应用.  相似文献   
35.
The computation of exact geodesics on triangle meshes is a widely used operation in computer-aided design and computer graphics. Practical algorithms for computing such exact geodesics have been recently proposed by Surazhsky et al. [5]. By applying these geometric algorithms to real-world data, degenerate cases frequently appear. In this paper we classify and enumerate all the degenerate cases in a systematic way. Based on the classification, we present solutions to handle all the degenerate cases consistently and correctly. The common users may find the present techniques useful when they implement a robust code of computing exact geodesic paths on meshes.  相似文献   
36.
2007年1-10月,我国的粗钢产量达到4.09亿吨,同比增长18.14%。10月单月产量4292.2万吨,再创单月产量新高;1-10月,钢材产量达4.67亿吨(含重复材),同比增长23.53%,10月钢材产量  相似文献   
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针对各校对大学生创业实训进行讲授内容的不同,我们在结合本专业的基础上,开展了网络创业实训课程,在创业方向方面不再仅限于网店,而是可以进行多种模式的选择,同时在提高实践性方向,最终的成果也以创业企划书来全面衡量。  相似文献   
39.
Random-effects regression modelling is proposed for analysis of correlated grouped-time survival data. Two analysis approaches are considered. The first treats survival time as an ordinal outcome, which is either right-censored or not. The second approach treats survival time as a set of dichotomous indicators of whether the event occurred for time periods up to the period of the event or censor. For either approach both proportional hazards and proportional odds versions of the random-effects model are developed, while partial proportional hazards and odds generalizations are described for the latter approach. For estimation, a full-information maximum marginal likelihood solution is implemented using numerical quadrature to integrate over the distribution of multiple random effects. The quadrature solution allows some flexibility in the choice of distributions for the random effects; both normal and rectangular distributions are considered in this article. An analysis of a dataset where students are clustered within schools is used to illustrate features of random-effects analysis of clustered grouped-time survival data.  相似文献   
40.
对纤维的需求不断增长,天然纤维缺口将愈来愈大,均为化纤发展带来了机遇。化纤工业竞争激烈,主要趋势为扩大规模提高效率。无人化、环保化也是一种趋势。同时也发展了一些与下游名牌产品联系在一起的小型专业厂.高技术、高性能纤维发展较快.在技术方面,认为纤维超细化、废弃物回收重新纺制纤维,注意环保,设备增容、高效化,高性能纤维开发等是主要趋势.  相似文献   
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