In this short paper we show that non-negative Ricci curvature is not preserved under Ricci flow for closed manifolds of dimensions four and above, strengthening a previous result of Knopf for complete non-compact manifolds of bounded curvature. This brings down to four dimensions a similar result Böhm and Wilking have for dimensions twelve and above. Moreover, the manifolds constructed here are...

The environment has a close relationship with people’s daily lives in China. Along with rapid economic growth and enrichment of social wealth, people have become more concerned about the standard of life, such as enjoying a clean, beautiful and comfortable environment. In response, the Chinese government has put forward a sustainable development plan, which strives to develop programs according...

This study analyzed the factors that caused intracranial infection after endoscopic resection of the pituitary tumors by transnasal-sphenoidal approach. A retrospective analysis was performed for 326 patients with resection of pituitary tumor, and multiple Logistic regression analysis was conduced for the relevant factors. Results showed that a total of 32 patients exhibited postoperative infec...

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This note points out that the assertions of [“Chen’s attractor exists if Lorenz repulsor exists: The Chen system is a special case of the Lorenz system,” CHAOS 23, 033108 (2013)] are groundless and incorrect. The failure of that criticism actually supports the strong standing of the Chen system.

The objective of this study was to evaluate the therapeutic safety and efficacy of percutaneous radiofrequency ablation (RFA) with Internally Cooled Electrode for malignant hepatic tumors; which were in contact with blood vessels. A total of 297 patients with malignant hepatic tumors (358 nodules) who underwent RFA, by means of straight Internally Cooled Electrodes, were enrolled in this study....