Objective To investigate and analysis the situation of malocclusion of 49 skulls of ancient resident in Xinjiang, and discuss the history evolution and the pathologic mechanism of malocclusion. Methods The investigation was carried out based on the standard of individual normal occlusion. Results Among the group of 49 skulls, the morbility rate of malocclusion was 30. 61% ; in Angle's classification of malocclution, class I was the most (73. 33%); in Mao's classification of malocclution, class I was also the most (33. 33%). Conclusion The morbility rate of malocclusion of resident in bronze age is lower than that of modern resident and nearer ages resident. There is a close releationship between the human food construction and the pathogenesis of malocclution.

Objective:To compare and analyze the clinical efficacy of hand-assisted laparoscopic surgery (HALS) and laparoscopic assisted surgery (LAS) in the treatment of advanced gastric cancer.Methods:Articles of the efficacy comparison of HALS and LAS in D2 radical gastrectomy for gastric cancer from 2000 to 2019 published in PubMed, Cochrane library, EM-BASE, China National Knowledge Infrastructure (CNKI), Wanfang, Weipu, Chinese full-text database of Chinese Sci-Tech journals, Chinese biomedical literature database were retrieved, and the literatures were screened according to the pre-established inclusion and exclusion criteria. The quality of the two groups was evaluated, and the short-term indexes and complications for meta-analysis of the two groups were analyzed by using Revman 5.3 software.Results:A total of 1277 patients were included in 10 articles, including 629 in the HALS group and 648 in the LAS group. The results of the meta-analysis showed that compared with the LAS group, the operation time was shorter in the HALS group (WMD=24.02, 95% CI: -40.41--7.62, P=0.004), but the auxiliary incision was slightly longer (WMD=0.27, 95% CI: 0.06-0.47, P=0.01), and there were no statistically significant difference in the remaining number of lymph node dissections (WMD=0.58, 95% CI: -1.22-2.39, P=0.53), intraoperative blood loss (WMD=-7.94, 95% CI: -16.21-0.33, P=0.06), gastrointestinal tract recovery time (WMD=0.00, 95% CI: -0.03- 0.04, P=0.85), total length of hospital stay (WMD=-0.14, 95% CI0: -0.36-0.09, P=0.23) and postoperative complications ( OR=0.89, 95% CI: 0.58-1.37, P=0.61). Conclusions:Compared with the LAS for D2 radical surgery of advanced gastric cancer, HALS has significantly shorter operation time and is easier to perform than LAS, but the incision length is slightly increased. Physicians can choose the appropriate operation method according to the specific conditions of the operation and themselves.

This study established a school-supervisor-postgraduate "three-dimensional interaction" mode of academic norms and ethics education for medical postgraduates based on their training characteristics. The mode was evaluated and improved in practice. The results showed that after the implementation of the mode, graduate students significantly improved their awareness of how to standardize the implementation of experiments [(79.86% vs. 89.47%); P=0.021] and how to write formal experimental records [(84.72% vs. 92.76%); P=0.028]. In addition, there were significant increases in the pass rate of pre defense (85.42% vs. 94.08%; P=0.014) and blind review (84.03% vs. 93.42%; P=0.010). The "three-dimensional interaction" mode truly helps to achieve a win-win-win situation between postgraduate supervisors and the school, and is worth further practice and promotion.

Objective To study the effects of different implantation angles of bi-leaflet mechanical heart valve(BMHV)on swirling flow in the aorta.Methods Based on the aortic CT images of a healthy volunteer,the effects of 4 different valve implantation angles(0°,45°,90° and 135°)on the aortic swirling flow under constant flow conditions were studied by computational simulation.Results The implantation of BMHV could seriously interfere with the aortic swirling flow,affecting the structure and helicity distributions of the swirling flow in ascending aorta,thus resulting in disturbed blood flows distal to the valve.The 135° implantation angle caused the most disruption to the swirling flow,leading to the largest areas of reversed swirling flows,while the 0° and 45° implantation angles caused relatively smaller damage to the swirling flow.The areas with low wall shear stress(<0.5 Pa)were the smallest when the implantation angle of BMHV was 0°.Conclusions At the implantation angle of 0°-45°,the disruption of BMHV to the swirling flow in ascending aorta was relatively small.Therefore,for different patients,the selection of implantation angle should be individualized according to the spatial geometry of their aorta(including the aortic sinuses),and the implantation angle can be determined between 0°-45°.