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Purpose In order to provide a scientific basis for the improvement of soda saline-alkaline paddy soil, the pot experiment was performed to explore the effects of rice straw and straw-derived biochar on the diversity of soil bacteria and community structure in soda saline-alkaline soil. Methods The experiment was four gradients of straw return (3 (RS1), 7.5 (RS2), 12 (RS3), and 16.5 (RS4) t/hm2) and four gradients of biochar return (3 (RB1), 7.5 (RB2), 12 (RB3), and 16.5 (RB4) t/hm2), using 0 t/hm2 as a control (CK). After 5 consecutive years of measuring straw returns, high-throughput sequencing was used to determine the relative abundance, alpha diversity, and changes in the community structure of soil bacteria. Result Our results demonstrated that straw return significantly increased the relative abundance of Bacteroidetes, Firmicutes, and Sphingomonas and significantly reduced the relative abundance of Acidobacteria, Actinobacteria, Gemmatimonadetes, Parcubacteria, Anaeromyxobacter, Pontibacter, uncultured_bacterium_f_Draconibacteriaceae, and Bryobacter. Straw-derived biochar return significantly increased the relative abundance of uncultured_bacterium_f_Draconibacteriaceae and significantly reduced the relative abundances of Actinobacteria, Gemmatimonadetes, Thiobacillus, and Anaeromyxobacter, indicating that both straw and its associated biochar return changed the relative abundance of the phyla and genera of some bacteria. Straw return affected bacteria phylum and genus more than straw-derived biochar. With the exception of the 16.5 t/hm2 straw return, which reduced bacterial richness, the treatments did not significantly impact alpha diversity. Compared with straw-derived biochar return, straw return significantly changed the bacterial community structure, and the higher the straw return, the higher the impact on the bacterial community structure. Redundancy analysis (RDA) demonstrated that there was a significant correlation between the physicochemical properties of the soil and the community structure of its bacteria. A Mantel test demonstrated that the content of available phosphorus, available potassium, and organic matter was all important environmental factors affecting community structure. Conclusion We speculate that straw return regulates the physicochemical properties of the soil, which affects the bacterial community structure.

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According to the safety principle, if one knows that p, one's belief that p could not easily have been false. One problem besetting this principle is the lottery problem – that of explaining why one does not seem to know that one will lose the lottery purely based on probabilistic considerations, prior to the announcement of the lottery result. As Greco points out, it is difficult for a safety theorist to solve this problem, without paying a heavy price. In this paper, I first reject three existing safety-based solutions to the lottery problem, due to Pritchard, Sosa, and Broncano-Berrocal. Failure of these accounts reveals that there is something crucial missing in the safety principle. By way of remedying this, I propose to integrate a safety principle with a condition regarding one's own awareness of (nearby) error-possibilities. The resulting account, as I argue, enjoys a number of theoretical advantages, including its capacity to handle the lottery problem.

Many find it an attractive idea that if one knows that p, one's belief that p must be safe-that is, the belief could not easily have been false (e.g., Pritchard, 2012;Sosa, 1999;Williamson, 2000). In terms of possible world semantics, a safe belief is true in the actual world, as well as in relevantly close possible worlds. Now, depending on the scope of 'close possible worlds', safety typically comes in the following varieties: