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Immunolocalization indicates that both original and regenerated lizard tail tissues contain populations of long retaining cells,putative stem/progenitor cells 下载免费PDF全文
Lorenzo Alibardi 《Microscopy research and technique》2015,78(11):1032-1045
The regeneration of the tail in lizards is likely sustained by stem/progenitor cells located in the stump after amputation of the tail. This microscopic and ultrastructural study shows the localization of 5‐bromo‐deoxy‐uridine (5BrdU)‐long retaining labeled cells in different tissues of the tail stump. These putative stem/progenitor cells are sparsely detected in the epidermis of scales, adipose tissue, intermuscle connective septa, myosatellite cells, and perichondrion of the vertebrae. Most of 5BrdU‐labeled cells are present in the bone marrow of vertebrae as hemocytoblasts and reticulate cells, whereas more numerous myelocytes and polychromatophilic erythroblasts show a variable level of nuclear labeling. 5BrdU and tritiated‐thymidine labeled and unlabeled hemopoietic cells are seen in circulating vessels and in the blastema where their maturation is completed. This observation indicates that the entire differentiation span of both white and red blood cells, at least during tail regeneration, lasts longer than 4 weeks. Labeled polychromatophilic erythroblasts and heterophilic and basophilic myelocytes are present in the synusoidal vessels of the regenerating tail. This study indicates that extravasating blood cells involved in immunity make large part of the forming blastema cell population, but are replaced by mesenchymal cells of different origin. The presence of long retaining labeled cells in tissues of the tail stump is likely connected to the production of blastema mesenchymal cells. Although no direct cell‐lineage study has been done, histological, immunocytochemical, and autoradiographic studies have indicated that it is from these tissues that proliferating cells appear mainly localized after tail amputation and blastema formation. Microsc. Res. Tech. 78:1032–1045, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
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Aleksandar M. Cvetkovic Danko Z. Milasinovic Aleksandar S. Peulic Nikola V. Mijailovic Nenad D. Filipovic Nebojsa D. Zdravkovic 《Computer methods and programs in biomedicine》2014
The main goal of this study was to numerically quantify risk of duodenal stump blowout after Billroth II (BII) gastric resection. Our hypothesis was that the geometry of the reconstructed tract after BII resection is one of the key factors that can lead to duodenal dehiscence. We used computational fluid dynamics (CFD) with finite element (FE) simulations of various models of BII reconstructed gastrointestinal (GI) tract, as well as non-perfused, ex vivo, porcine experimental models. As main geometrical parameters for FE postoperative models we have used duodenal stump length and inclination between gastric remnant and duodenal stump. Virtual gastric resection was performed on each of 3D FE models based on multislice Computer Tomography (CT) DICOM. According to our computer simulation the difference between maximal duodenal stump pressures for models with most and least preferable geometry of reconstructed GI tract is about 30%. We compared the resulting postoperative duodenal pressure from computer simulations with duodenal stump dehiscence pressure from the experiment. Pressure at duodenal stump after BII resection obtained by computer simulation is 4–5 times lower than the dehiscence pressure according to our experiment on isolated bowel segment. Our conclusion is that if the surgery is performed technically correct, geometry variations of the reconstructed GI tract by themselves are not sufficient to cause duodenal stump blowout. Pressure that develops in the duodenal stump after BII resection using omega loop, only in the conjunction with other risk factors can cause duodenal dehiscence. Increased duodenal pressure after BII resection is risk factor. Hence we recommend the routine use of Roux en Y anastomosis as a safer solution in terms of resulting intraluminal pressure. However, if the surgeon decides to perform BII reconstruction, results obtained with this methodology can be valuable. 相似文献
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用Boosting方法组合增强Stumps进行文本分类 总被引:11,自引:0,他引:11
为提高文本分类的精度,Schapire和Singer尝试了一个用Boosting来组合仅有一个划分的简单决策树(Stumps)的方法.其基学习器的划分是由某个特定词项是否在待分类文档中出现决定的.这样的基学习器明显太弱,造成最后组合成的Boosting分类器精度不够理想,而且需要的迭代次数很大,因而效率很低.针对这个问题,提出由文档中所有词项来决定基学习器划分以增强基学习器分类能力的方法.它把以VSM表示的文档与类代表向量之间的相似度和某特定阈值的大小关系作为基学习器划分的标准.同时,为提高算法的收敛速度,在类代表向量的计算过程中动态引入Boosting分配给各学习样本的权重.实验结果表明,这种方法提高了用Boosting组合Stump分类器进行文本分类的性能(精度和效率),而且问题规模越大,效果越明显. 相似文献
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Cassava (Manihot esculenta Crantz) stump biochar: Physical/chemical characteristics and dye affinity
L. Meili R. P. S. Godoy J. I. Soletti S. H. V. Carvalho L. M. O. Ribeiro M. G. C. Silva 《Chemical Engineering Communications》2019,206(7):829-841
Aiming investigated the pyrolysis of the agricultural waste known as cassava stump, the portion of the plant to which the tuberous roots and aerial parts of the plant are attached, this study had as objective to produce biochars from cassava stump by conducting vacuum pyrolysis at 400, 500, or 600?°C. The biochars were characterized by proximate analysis, thermogravimetric analysis, Fourier-transform infrared absorption spectroscopy, X-ray diffraction, scanning electron microscopy, and nitrogen adsorption. Adsorption affinity tests were performed with four different dyes: methylene blue, basic fuchsin, acid fuchsin, and alizarin. Biochar obtained at 500?°C, heating rate of 20?°C.min?1, and 90?min of residence at the final temperature, had 22% higher fixed carbon content as compared to the other biochars and 3.16 times greater fixed carbon content than the original cassava stump. This biochar showed the best adsorption capacity (0.0679?mmol/g) and percentage of removal (87.6%) of methylene blue dye from aqueous solution. The material characterization reveals that biochars from Manihot esculenta Crantz stump may have potential application in carbon sequestering. Besides that, these biochars could be applied with efficiency as adsorbent of dyes. 相似文献
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有肋梁墩式筏板基础是由柱墩、基础梁和基础底板组成,柱荷载通过柱墩扩散到基础梁和基础底板,最后传到地基.与一般的筏板基础有所不同,由于有柱墩,有肋梁墩式筏板基础梁的内力需按变截面梁计算.本文导出了变截面梁的固端弯矩和剪力,给出了多跨变截面连续梁的弯矩系数和剪力系数,并通过实例说明带柱墩的刚性基础梁计算方法. 相似文献
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文章主要阐述树根桩在软弱地基中的施工方法,同时说明树根桩与其它桩型比较,施工受周边环境影响小、节省造价的特点。 相似文献
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The purpose of this study is to find the determinants of the profits for the Development and Investment Banks (IaDB) in Turkey. In Turkish Banking System, the main financial source of the banks is the deposits, which constitute almost%60 of the balance sheet. As being a sub-group of the banking system, IaDB are not allowed to accept deposits in Turkey, which changes the total structure of the profitability compared to other banks. Till today, none of the relevant research was concentrated on the profit structure of the IaDB neither in Turkey nor in any other countries. Such research would fill that unexpectedly disregarded yet highly important gap.Therefore, to address this gap, quarterly financial data (10 balance sheet ratios) of 13 banks in the period of 2002Q4-2014Q3 were utilized. As a profit measurement among all other available measures, Return on Equity was chosen as dependent variable as it was the most used one as well as many other researcher have preferred as well. This study investigates the potential usage of bagging (Bag), which is one of the most popular ensemble learning methods, in building ensemble models, is used to predict the determinants of Turkish IaDB profitability. Three well-known tree-based machine learning (ML) models (i.e., Decision Stump (DStump), Random Tree (RTree), Reduced Error Pruning Tree (REPTree)) are deployed as base learner. This empirical study indicates that bagging ensemble models (i.e., Bag-DStump, Bag-RTree, Bag-MLP and Bag-REPTree) are superior to their base learners and could improve the prediction accuracy of individual ML models (i.e., DStump, RTree, REPTree). 相似文献
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武汉地区近年来多采用小孔径抗浮锚杆桩对地下室进行抗浮加固,但通常会有少部分锚杆达不到设计抗拔力。为解决这一问题,利用支护桩的抗拔力来弥补锚杆桩的不足,从而有效地解决了地下室抗浮难题,为类似的工程问题提供了参考。 相似文献