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Background It is very difficult to contain persistently high incidence and mortality rates of gastric cancer. Moreover, the age at onset of gastric cancer is becoming earlier. However, there are few studies on the prediction of the age at gastric cancer onset. Objective To investigate the relationship between single nucleotide polymorphisms (SNPs) in mitochondrial displacement loop (D-Loop) and age at gastric cancer onset. Methods A total of 150 patients with confirmed gastric cancer by pathologically examination of biopsy samples taken during gastroscopy were recruited from Department of Gastroenterology, the Fourth Hospital of Hebei Medical University between July 2007 and December 2008. PCR was used to amplify the targeted fragment of peripheral blood mitochondrial DNA, and the mitochondrial D-Loop region was sequenced. Survival curves for patients with different ages of onset of gastric cancer were plotted by the Kaplan-Meier method, and compared by the Log-rank test. Cox regression analysis was used to identify factors associated with age of onset of gastric cancer. Results The age of onset of patients with different degrees of education was statistically significant (P

Aiming at the problems of low single-seed rate, high rate of missing seeds, high rate of multiple seeds, and low rate of upright seeds in the mechanized sowing of garlic seeds, this paper proposes a structural design scheme of a type hole wheel garlic seed metering device based on the characteristics of garlic species. Based on the agronomic requirements of garlic planting and the characteristics of garlic species, the mechanism of the hole wheel structure to improve the seed filling performance of the seed metering device was clarified, a structural parameter design of the key components of the device was established through theoretical calculations, and a single-factor simulation test was conducted using the Engineering Discrete Element Modelling (EDEM) software. Using the Design-Expert 11 data analysis software, a mathematical regression model of each test factor and test index was established, and the test factors were analyzed. The parameters were optimized, and the following was found to be the optimum parameter combination: seeding wheel speed of 30 rpm, profile hole depth of 18 mm, and adjustment length of the profile hole of 41 mm. The EDEM simulation test results showed a single-seed rate of 91.67% and a missing seed rate of 4.17%. The bench test results showed a single-seed rate of 89.2%, a missing seed rate of 5.0%, and a multiple seed rate of 5.8%. The field test results showed a single-seed rate of 88.44%, a multiple seed rate of 4.11%, a missing seed rate of 7.44%, a breakage rate of 1.11%, and an upright rate of 62.36%. The errors between the bench test/field test and the discrete element simulation test results were 2.7% and 3.5%, respectively, which were consistent with the simulation results, thus meeting the requirements of single-seed sowing using the garlic seed metering device. [ABSTRACT FROM AUTHOR]