17,832 research outputs found
The Positive Effect of Negative Word-of-mouth on Consumers’ Purchase Intention Towards Experience Goods
The purpose of the present study is to examine the positive effect of negative word-of-mouth on consumers’ purchase intention towards an experience good. By introducing consumer’s need for closure as a moderator, the results of two situation-based experiments reveal that negative word-of-mouth of a well-known experience good would increase the purchase intention of consumers with a high-level need for closure (Vs. a low-level need for closure); the same effect would not happen to an unknown experience good; and the positive effect of negative word-of-mouth on the purchase intention of consumers with a high-level need for closure towards a well-known experience good only happens in the case of negative word-of-mouth for the first time (Vs. the second time). The findings contribute to the literature on online review and word-of-mouth from a new perspective
Advances in fault diagnosis for high-speed railway: A review
The high speed railway (HSR) is a complex system with many subsystems and components. The reliability of its core subsystems is a key consideration in ensuring the safety and operation efficiency of the whole system. As the service time increases, the degradation of these subsystems and components may lead to a range of faults and deteriorate the whole system performance. To ensure the operation safety and to develop reasonable maintenance strategies, fault detection and isolation is an indispensable functionality in high speed railway systems. In this paper, the traction power supply system, bogie system, civil infrastructure system, and control and signaling system of HSR are briefly summarized, and then different fault diagnosis methods for these subsystems are comprehensively reviewed. Finally, some future research topics are discussed
Site-specific selection reveals selective constraints and functionality of tumor somatic mtDNA mutations.
BACKGROUND: Previous studies have indicated that tumor mitochondrial DNA (mtDNA) mutations are primarily shaped by relaxed negative selection, which is contradictory to the critical roles of mtDNA mutations in tumorigenesis. Therefore, we hypothesized that site-specific selection may influence tumor mtDNA mutations.
METHODS: To test our hypothesis, we developed the largest collection of tumor mtDNA mutations to date and evaluated how natural selection shaped mtDNA mutation patterns.
RESULTS: Our data demonstrated that both positive and negative selections acted on specific positions or functional units of tumor mtDNAs, although the landscape of these mutations was consistent with the relaxation of negative selection. In particular, mutation rate (mutation number in a region/region bp length) in complex V and tRNA coding regions, especially in ATP8 within complex V and in loop and variable regions within tRNA, were significantly lower than those in other regions. While the mutation rate of most codons and amino acids were consistent with the expectation under neutrality, several codons and amino acids had significantly different rates. Moreover, the mutations under selection were enriched for changes that are predicted to be deleterious, further supporting the evolutionary constraints on these regions.
CONCLUSION: These results indicate the existence of site-specific selection and imply the important role of the mtDNA mutations at some specific sites in tumor development
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