Objective. Learning the structures and unknown correlations of a motor imagery electroencephalogram (MI-EEG) signal is important for its classification. It is also a major challenge to obtain good classification accuracy from the increased number of classes and increased variability from different people. In this study, a four-class MI task is investigated. Approach. An end-to-end novel hybrid deep learning scheme is developed to decode the MI task from EEG data. The proposed algorithm consists of two parts: a. A one-versus-rest filter bank common spatial pattern is adopted to preprocess and pre-extract the features of the four-class MI signal. b. A hybrid deep network based on the convolutional neural network and long-term short-term memory network is proposed to extract and learn the spatial and temporal features of the MI signal simultaneously. Main results. The main contribution of this paper is to propose a hybrid deep network framework to improve the classification accuracy of the four-class MI-EEG signal. The hybrid deep network is a subject-independent shared neural network, which means it can be trained by using the training data from all subjects to form one model. Significance. The classification performance obtained by the proposed algorithm on brain–computer interface (BCI) competition IV dataset 2a in terms of accuracy is 83% and Cohen’s kappa value is 0.80. Finally, the shared hybrid deep network is evaluated by every subject respectively, and the experimental results illustrate that the shared neural network has satisfactory accuracy. Thus, the proposed algorithm could be of great interest for real-life BCIs.

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Problem definition: This paper examines the economic effects of the fulfillment services offered by Amazon (FBA) to the third-party sellers on its retail platform. Academic/practical relevance: Logistics is critical for e-commerce. It is intriguing that the third-party sellers that use FBA may directly compete with Amazon. By FBA, their service levels are substantially improved and so is their competitiveness. Such a phenomenon has been little investigated in prior literature. Methodology: We develop a strategic competition model where Amazon and a representative third-party seller engage in both price and service competition. Results: Interestingly, we find that although FBA may intensify the service competition between Amazon and the third-party seller, it can mitigate their price competition besides the direct revenue Amazon collects from the service. The latter effects dominate the former when the cross-service sensitivity of the consumers is either sufficiently low or sufficiently high. Therefore, not only the third-party sellers but also Amazon may benefit from FBA. Moreover, because the sales of Amazon’s products may increase because of FBA, its OEM (original equipment manufacturer) supplier may gain from FBA also. These findings extend to the settings where the third-party seller is Amazon’s OEM supplier, cross-price and cross-service sensitivities are correlated, or the parties set their retail prices sequentially. Managerial implications: Our analysis provides insights about when FBA is more likely to be beneficial and when it can be harmful. They are useful for understanding the impacts of FBA on both Amazon and the third-party sellers.

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Fluoride-induced ameloblast apoptosis is a key event in dental fluorosis development. Forkhead box o1 (Foxo1) is a transcription factor involved in cell apoptosis. The present study aims to investigate the effect of Foxo1 on ameloblast apoptosis induced by fluoride in vitro and to explore its possible mechanism. Ameloblast-like cells (LS8 cells) were exposed to various concentrations of NaF for up to 48 h. Foxo1 activation was modulated using lentiviral vectors, and cell apoptosis was measured by flow cytometry. The expression levels of Foxo1, c-Jun N-terminal kinase (JNK), and some well-known regulators of the mitochondrial pathway of apoptosis (cytoplasmic cytochrome c, cleaved caspase-9, cleaved caspase-3, Bcl-2, and Bax) were detected by quantitative real-time PCR, western blot, and immunofluorescence assay. The results showed significantly decreased expression and increased phosphorylation of Foxo1 in NaF-treated LS8 cells. Further investigation revealed that forced Foxo1 activation with lentiviral vectors attenuated NaF-induced apoptosis of LS8 cells, markedly decreasing protein levels of cytoplasmic cytochrome c, cleaved caspase-9, and cleaved caspase-3 while increasing the Bcl-2/Bax ratio and JNK expression level. These findings suggest that Foxo1 attenuated NaF-induced apoptosis of LS8 cells via inhibiting the mitochondrial pathway and activating JNK.